Carbon ion generator

Abstract

A laser-driven ion acceleration carbon ion generating device, wherein generation of impurity ions is suppressed. A carbon ion generating device (10) generates a carbonized region (22) by irradiating a film (21) that is a film made of an organic compound with a first laser light (laser light L1), and generating carbon ions by irradiating at least a portion of the carbonized region (22) with a second laser light (laser light L2).

Description

Technical Field

[0001] The present invention relates to a carbon ion generator.

Background Art

[0002] In heavy particle beam cancer treatment, carbon ions generated in a carbon ion generator are accelerated to a predetermined energy using a linear accelerator and a synchrotron, and then the accelerated carbon ions are irradiated onto a tumor.

[0003] Non-Patent Document 1 describes a carbon ion generator that generates carbon ions by irradiating a carbon film with high-power laser light. This method is called a laser-driven ion acceleration method. When high-power laser light is irradiated onto one surface of the film (hereinafter referred to as the front surface), a large number of high-speed electrons jump out from the other surface of the film (hereinafter referred to as the back surface). As a result, a strong polarization electric field on the order of TV / m is generated in the vicinity of the back surface, and carbon ions jump out from the film by being accelerated by the polarization electric field. Therefore, a carbon ion generator using the laser-driven ion acceleration method can generate carbon ions in an accelerated state.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, conventional carbon ion generators using a laser-driven ion acceleration method have a problem of generating impurity ions other than carbon ions (for example, oxygen ions) together with carbon ions. This is because impurity molecules such as water molecules are adsorbed on the surface of the film, forming an impurity layer.

[0006] One aspect of the present invention has been made in view of the above-described problems, and an object thereof is to suppress the generation of impurity ions in a carbon ion generator using a laser-driven ion acceleration method.

Means for Solving the Problems

[0007] In order to solve the above problems, a carbon ion generator according to one aspect of the present invention includes a first laser irradiation mechanism that carbonizes a part of a film made of an organic compound by irradiating the part with a first laser beam to generate a carbonized region, and a second laser irradiation mechanism that generates carbon ions from the carbonized region by irradiating at least a part of the carbonized region with a second laser beam.

Effects of the Invention

[0008] According to one aspect of the present invention, in a carbon ion generator using a laser-driven ion acceleration method, the generation of impurity ions can be suppressed.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] 〔First Embodiment〕 The carbon ion generator 10 according to the first embodiment of the present invention will be described with reference to FIG. 1. FIG. 1(a) is a schematic diagram of the carbon ion generator 10. FIG. 1(b) is an enlarged cross-sectional view of the carbonized region of the film used in carbon ion generation in the carbon ion generator 10. The carbon ion generator 10 can generate carbon ions (C 4+ ). The generated carbon ions can be used, for example, as carbon ions for irradiating tumors in heavy particle beam cancer treatment.

[0011] <Carbon ion generator> As shown in FIG. 1(a), the carbon ion generator 10 includes a chamber 11, a laser light source 12, a lens 13, a mirror 14, a laser light source 15, and a condenser mirror 16.

[0012] (Chamber) The chamber 11 is a container made of metal (stainless steel in this embodiment) and having a cylindrical shape. In FIG. 1(a), the shape of the chamber 11 is simply illustrated using a single solid line. However, the actual chamber 11 has an appropriately set thickness.

[0013] The chamber 11 is configured to be able to seal its internal space. A vacuum pump (not shown in FIG. 1(a)) is connected to the chamber 11. The vacuum pump evacuates the internal space of the chamber 11 to keep the pressure in the internal space lower than the atmospheric pressure. In this embodiment, the pressure in the internal space of the chamber 11 is about 1×10 -2 Pa. However, the pressure is not limited to this and can be set as appropriate.

[0014] As shown in Fig. 1(a), the chamber 11 is provided with two ports 111 and 112. Each of the ports 111 and 112 is a port for optical input and output, and is a plate-like member made of glass that is transparent to the laser beams L1 and L2 described later, and is composed of a plate-like member made of fused quartz. As will be described later, the laser beam L1 has a central wavelength of 532 nm, and the laser beam L2 has a central wavelength of 810 nm. However, the material constituting the ports 111 and 112 is not limited to fused quartz, and any material that has translucency in the visible to infrared regions may be used. In the following, the central wavelengths of the laser beams L1 and L2 are also simply referred to as the wavelengths of the laser beams L1 and L2.

[0015] (First laser light source) The laser light source 12 emits a laser beam L1. The laser beam L1 is irradiated onto a film 21 which is a film made of an organic compound in-situ so that the organic compound constituting the film 21 is in-situ carbonized to generate a carbonized region 22, and its wavelength and output are determined accordingly. Fig. 1(b) shows only the carbonized region 22 of the film 21.

[0016] In this embodiment, a semiconductor laser that emits a laser beam L1 with a wavelength of 532 nm is adopted as the laser light source 12. Also, in this embodiment, the laser light source 12 is set so that the output of the laser beam L1 at the beam spot P1 described later is about 520 mW. However, the wavelength and output of the laser beam L1 can be appropriately selected within the range that can carbonize the organic compound constituting the film 21.

[0017] The laser light source 12 and the laser beam L1 are each an example of a first laser light source and a first laser beam, respectively. The laser light source 12 is arranged so that the laser beam L1 enters the internal space of the chamber 11 from the port 111.

[0018] Although not shown in FIG. 1(a), a collimating lens is provided downstream of the laser light source 12. Therefore, this collimating lens converts the laser light L1, which is divergent light emitted from the laser light source 12, into collimated light.

[0019] A lens 13 and a mirror 14 are provided on the optical axis of the laser light L1 in the internal space of the chamber 11. The lens 13 converts the laser light L1, which is collimated light, into convergent light. The mirror 14 reflects the laser light L1, thereby irradiating a partial region of one main surface of the film 21 (the main surface on the positive z-axis side in FIG. 1(a)) with the convergent laser light L1. In this way, the laser light L1 incident from the port 111 into the internal space of the chamber 11 is irradiated onto a partial region of one main surface of the film 21 via the lens 13 and the mirror 14. Note that the laser light source 12, the lens 13, and the mirror 14 are an example of a first laser irradiation mechanism that carbonizes a partial region of the film 21 irradiated with the laser light L1 by irradiating the laser light L1. Also, the beam spot P1 is an example of a region on one main surface of the film 21 where the laser light L1 is irradiated. In the present embodiment, the diameter of the beam spot P1 is about 300 μm, and its area is about 0.09 mm 2 2. When the laser light L1 has a sufficiently high output to carbonize the organic compound contained in the beam spot P1, the lens 13 can be omitted.

[0020] The optical axis of the laser light L1 is inclined from a direction parallel to the normal of the film 21 (the z-axis direction shown in FIG. 1). In the present embodiment, the first inclination angle, which is the angle formed by the optical axis of the laser light L1 and the normal of the film 21, is about 30°. However, the first inclination angle is not limited to this and can be set as appropriate. The first inclination angle may be 0° (i.e., the optical axis of the laser light L1 is parallel to the normal of the film 21).

[0021] The wavelength, output, and area of the laser beam L1 are preferably determined so as to heat the temperature of the film 21 at the beam spot P1 to 600 °C or higher. For example, the laser beam L1 has a wavelength of 532 nm, and the area of the beam spot P1 is 0.09 mm 2 In the case of this, the output at the beam spot P1 is preferably 360 mW or more. According to this configuration, the temperature of the film 21 at the beam spot P1 can be heated to 600 °C or higher.

[0022] (Second laser light source) The laser light source 15 emits a laser beam L2. When the film 21 is irradiated with the laser beam L2, carbon ions (C 4+ ) are generated from the carbonized region 22. In the present embodiment, as the laser light source 15, center a Ti:sapphire laser that emits a laser beam L2 having a wavelength of 810 nm and a pulse width of 80 fsec is adopted. Further, in the present embodiment, the energy per pulse of the laser beam L2 is about 500 mJ, and the optical axes of the laser light source 15 and the laser beam L2 are set so that the diameter of the beam spot P2 described later is 2 μm or more and 3 μm or less. Therefore, in the present embodiment, the diameter of the beam spot P2 is 1 / 100 times or less of the diameter of the beam spot P1. However, the wavelength and the energy per pulse of the laser beam L2 can be appropriately selected within the range in which carbon ions can be generated from the carbonized region 22.

[0023] In this embodiment, a carbonized region 22 is formed by irradiating a laser beam L1 onto a beam spot P1. Then, while irradiating the carbonized region 22 with the laser beam L1, a laser beam L2 is irradiated onto a beam spot P2. That is, the laser beam L1 and the laser beam L2 are simultaneously irradiated onto the carbonized region 22. According to this configuration, sufficient time can be ensured for carbonizing the polyimide resin contained in the beam spot P1. However, each of the laser beam L1 and the laser beam L2 may be configured to irradiate the laser beam L2 after irradiating the laser beam L1, instead of irradiating them simultaneously. In this case, the irradiation interval, which is the time from irradiating the laser beam L1 to irradiating the laser beam L2, is preferably as short as possible. When the pressure in the internal space of the chamber 11 is about 1×10 -2 Pa, it is preferably 5 seconds or less. The longer the irradiation interval becomes, the more the effect associated with irradiating the laser beam L1 (i.e., removal of the impurity layer) decreases. Therefore, the longer the irradiation interval becomes, the fewer the number and maximum energy of the generated carbon ions, and the more the number and maximum energy of the generated hydrogen ions (H + ) increase. Note that the irradiation interval will be described later with reference to FIG. 4.

[0024] As shown in FIG. 1(a), the optical axis of the laser beam L2 is determined such that the beam spot P2 is included in the beam spot P1, and more preferably, the center of the beam spot P2 substantially coincides with the center of the beam spot P1. That is, the laser light source 15 is configured to irradiate the laser beam L2 onto at least a part of the beam spot P1 while the laser beam L1 is being irradiated. Note that the adjustment of the optical axis of the laser beam L2 may be performed while observing the beam spot P1 using a high-magnification camera.

[0025] Each of the laser light source 15 and the laser beam L2 is an example of a second laser light source and a second laser beam, respectively. The laser light source 15 is arranged such that the laser beam L2 enters the internal space of the chamber 11 from the port 112.

[0026] Although not shown in Fig. 1(a), a collimating lens is provided downstream of the laser light source 15. Therefore, this collimating lens converts the laser light L2, which is divergent light emitted from the laser light source 15, into collimated light.

[0027] A condensing mirror 16 is provided on the optical axis of the laser light L2 within the internal space of the chamber 11. The condensing mirror 16 reflects the laser light L2, which is collimated light, while converting it into convergent light, and irradiates the beam spot P2, which is a part of the other main surface of the film 21 (the main surface on the negative z-axis side in Fig. 1(a)), with the convergent laser light L2. In the present embodiment, an off-axis paraboloidal mirror is employed as the condensing mirror 16. Thus, the laser light L2 that has entered the internal space of the chamber 11 from the port 112 is irradiated onto the beam spot P2, which is a part of the other main surface of the film 21, via the condensing mirror 16. Note that the laser light source 15 and the condensing mirror 16 are an example of a second laser irradiation mechanism that generates carbon ions from the carbonization region 22 by irradiating at least a part of the carbonization region 22 with the laser light L2. Also, the beam spot P 2 is an example of a region where the laser light L2 is irradiated in the carbonization region 22.

[0028] In the present embodiment, the optical axis of the laser light L2 is inclined from the direction parallel to the normal of the film 21 (the z-axis direction shown in Fig. 1). In the present embodiment, the second inclination angle, which is the angle formed by the optical axis of the laser light L2 and the normal of the film 21, is approximately 43°. However, the second inclination angle is not limited to this and can be set as appropriate. The second inclination angle may be 0° (i.e., the optical axis of the laser light L2 is parallel to the normal of the film 21).

[0029] (Film) The film 21 is held in a planar manner in its entirety including the beam spot P1 and the beam spot P2 by a holding portion. The mechanism by which the holding portion holds the film 21 is not limited and can be appropriately selected. Note that the illustration of the holding portion is omitted in Fig. 1.

[0030] In this embodiment, as the film 21 for irradiating the laser light L1 and the laser light L2, a square polyimide resin film is adopted. The film 21 is larger than the beam spots P1 and P2. In this embodiment, the thickness of the film 21 is 5 μm. However, the shape of the film 21 is not limited to a square shape and can be appropriately selected.

[0031] The polyimide resin is an example of an organic compound. Note that the material constituting the film 21 is not limited to the polyimide resin. Examples of other organic compounds constituting the film 21 include polyester resin and polypropylene resin.

[0032] Also, the thickness of the film 21 is not limited to 5 μm, but is preferably 100 nm or more and 12.5 μm or less. More preferably, the thickness of the film 21 is 1 μm or more and 5 μm or less.

[0033] The thinner the thickness of the film 21, the higher the acceleration energy of the carbon ions generated from the film 21 can be increased. Further, when the thickness of the film 21 is 100 nm or more, more preferably 1 μm or more, breakage that may occur in the carbonized region 22 can be suppressed, and an interaction can be surely generated between the laser light L2 and the carbonized region 22.

[0034] Also, a reinforcing layer for reinforcing the organic compound film may be laminated or coated on one main surface of the film 21. As the reinforcing layer, a film made of a material having a higher intensity when irradiated with the laser light L1 compared to the organic compound is suitable. Examples of such a material include metals with high chemical stability on the surface (for example, nickel, gold, etc.).

[0035] (Principle of carbon ion generation) By irradiating the film 21 with the laser beam L1, the color of the polyimide resin contained in the beam spot P1 changes to black, and a carbonized region 22 is formed in the region including the beam spot P1. In Fig. 1(b), an enlarged cross-section of the carbonized region 22 of the film 21 including the beam spot P2 irradiated with the laser beam L2 is shown. Note that the diameter of the beam spot P1 is about 100 times larger than the diameter of the beam spot P2 as described above. Therefore, the beam spot P1 is not shown in Fig. 1(b). In Fig. 1(b), 0° is adopted as the second inclination angle which is the angle formed by the optical axis of the laser beam L2 and the normal of the film 21. Also, in Fig. 1(b), the beam spot P2 and the ion generation region P3 are shown by thick solid lines.

[0036] Hereinafter, among the pair of main surfaces constituting the carbonized region 22, the main surface on the side irradiated with the laser beam L2 is referred to as the front surface 221, and the main surface on the side opposite to the front surface (in this embodiment, the main surface on the side irradiated with the laser beam L1) is referred to as the back surface 222.

[0037] As shown in Fig. 1(b), when the laser beam L2 is irradiated onto the beam spot P2 included in the front surface 221 of the carbonized region 22, the electrons existing in the vicinity of the beam spot P2 of the carbonized region 22 vibrate violently due to the interaction generated with the laser beam L2, and are accelerated in the direction from the front surface 221 to the back surface 222 (in Fig. 1(b), the positive z-axis direction), and jump out from the ion generation region P3 of the back surface 222 to the outside of the carbonized region 22. At this time, the electrons that have jumped out from the back surface 222 to the outside of the carbonized region 22 between generate a polarization electric field with the carbon ions remaining in the carbonized region 22. In Fig. 1(b), the range of the region where the laser beam L2 propagates inside the carbonized region 22 is schematically shown by a virtual line (two-dot chain line).

[0038] The carbon ions remaining in the carbonization region 22 are accelerated by this polarization electric field and jump out from the back surface 222 to the outside of the carbonization region 22. The energy distribution of the carbon ions that have jumped out from the carbonization region 22 can be measured, for example, using a Thomson parabola ion analyzer. In Fig. 1(b), the shape of the region where the carbon ions that have jumped out in the space located on the back surface 222 side of the carbonization region 22 are distributed is schematically shown by a virtual line (two-dot chain line).

[0039] As described above, the carbon ions that jump out from the back surface 222, which is the main surface on the opposite side of the front surface 221 irradiated with the laser beam L2, are called forward-accelerated ions. Also, as described in Phys. Rev. Lett. 99, 185002 (2007), when the laser beam L2 with a small ratio of background light (pre-pulse) to the main pulse is irradiated on the front surface 221, it is known that carbon ions also jump out from the front surface 221. Thus, the carbon ions that jump out from the front surface 221 are called backward-accelerated ions. As the carbon ions to be irradiated on the tumor in heavy particle beam cancer treatment, either forward-accelerated ions or backward-accelerated ions can be used.

[0040] Also, as described above, when using, as the film 21, a film having a reinforcing layer laminated or coated on one of the main surfaces, the main surface on which the reinforcing layer is provided may be determined according to whether forward-accelerated ions or backward-accelerated ions are used for treatment. For example, when using the forward-accelerated ions shown in Fig. 1(b) for treatment, since the ions jump out from the back surface 222, the reinforcing layer may be provided on the front surface 221. Also, when using backward-accelerated ions for treatment, since the ions jump out from the front surface 221, the reinforcing layer may be provided on the back surface 222. Note that the laser beam L1 carbonizes the film 21 included in the vicinity of the beam spot P1 and removes the impurity layers formed on the front surface 221 and the back surface 222 regardless of which main surface of the front surface 221 and the back surface 222 is irradiated. Therefore, regardless of whether forward-accelerated ions or backward-accelerated ions are used for treatment, the laser beam L2 may be irradiated on either the front surface 221 or the back surface 222.

[0041] (First Embodiment and Second Embodiment Group) In the carbon ion generator 10 described above, when 0 second is adopted as the irradiation interval, which is the time from the irradiation of the laser beam L1 to the irradiation of the laser beam L2, it is taken as the first embodiment of the present invention. Further, in the carbon ion generator 10 described above, when 1 second, 5 seconds, 15 seconds, and 60 seconds are adopted as the irradiation interval, it is taken as the second embodiment group of the present invention. Further, in the carbon ion generator 10 described above, when the irradiation of the laser beam L1 is omitted and only the laser beam L2 is irradiated to the beam spot P2, it is taken as a comparative example with respect to the first embodiment and the second embodiment group. Hereinafter, this comparative example is referred to as the first comparative example. Note that, regarding the parameters other than the irradiation interval, they are as described above.

[0042] Each of FIGS. 2(a) and 2(b) is an image showing the energy distribution of ions generated using the first comparative example and the first embodiment of the present invention. In FIGS. 2(a) and 2(b), the horizontal axis represents an index corresponding to the energy of the generated ions, and the emission intensity represents the amount of the generated ions. Note that the closer the horizontal axis is to 0 mm, the greater the energy of the generated ions.

[0043] FIG. 3 is the present invention a graph showing the energy spectra of carbon ions generated using the first comparative example and the first embodiment of the present invention.

[0044] Referring to FIGS. 2(a) and 2(b) and FIG. 3, by irradiating the laser beam L1 simultaneously with the laser beam L2, the maximum energy of the carbon ions increased 3.4 times from 2.5 MeV to 8.5 MeV as compared with the case where only the laser beam L2 was irradiated. Also, the generation amount of the carbon ions increased approximately 20 times by irradiating the laser beam L1 simultaneously with the laser beam L2. Note that the generation amount of the carbon ions is obtained by integrating dI / dE in the graph shown in FIG. 3. Further, it was found that by irradiating the laser beam L1 simultaneously with the laser beam L2, generation of hydrogen ions, which are impurity ions, can be suppressed along with an increase in the generation amount of the carbon ions.

[0045] Each image in FIG. 4 is an image showing the energy distribution of ions generated by the first embodiment of the present invention and when the irradiation intervals were changed to 1 second, 5 seconds, 15 seconds, and 60 seconds in the second embodiment group of the present invention. Each of the horizontal axis and the vertical axis in FIG. 4 is the same as the horizontal axis and the vertical axis in FIGS. 2(a) and 2(b).

[0046] Referring to FIG. 4, it was found that the ions generated by each of the second embodiment groups contained more carbon ions than the first comparative example (see FIG. 2(a)), and generation of hydrogen ions, which are impurity ions, can be suppressed. However, it was found that as the irradiation interval was lengthened, the emission intensity of the carbon ions decreased and the spectrum of the carbon ions shifted to the low energy side. Also, it was found that as the irradiation interval was lengthened, the emission intensity of the hydrogen ions increased and the spectrum of the hydrogen ions shifted to the high energy side. From the results of FIG. 4, it was determined that if the irradiation interval is 5 seconds or less, the results are not significantly different from those of the first embodiment. That is, the irradiation interval is preferably 5 seconds or less.

[0047] (Third Embodiment) In the carbon ion generation device 10 described above, the case where 0 seconds is adopted as the irradiation interval, which is the time from irradiating the laser beam L1 to irradiating the laser beam L2, is taken as the third embodiment of the present invention. Further, in the carbon ion generation device 10 described above, the case where the irradiation of the laser beam L1 is omitted and only the laser beam L2 is irradiated to the beam spot P2 is taken as a comparative example with respect to the third embodiment. Hereinafter, this comparative example is referred to as the second comparative example. Note that the third embodiment is different from the first embodiment in that the pulse width is 45 fsec., the energy per pulse of the laser beam L2 is about 8 J, and the beam spot diameter of the beam spot P2 is about 1.5 μm.

[0048] Each of FIGS. 5(a) and 5(b) is a graph showing the depth dependence of the composition ratio of the film used in the second comparative example and the third embodiment, respectively. In the second comparative example, since the irradiation of the laser beam L1 is omitted, the material constituting the film remains polyimide. On the other hand, in the third embodiment, the carbonized region 22 is formed by irradiating the laser beam L1. FIG. 5(b) shows the result of measuring the depth dependence of the composition ratio of the carbonized region 22. The composition ratio was measured using X-ray photoelectron spectroscopy (XPS). Further, the depth dependence of the composition ratio was obtained by milling the surface of the film by sputtering the surface of the film using a gas cluster ion beam in the chamber and measuring XPS each time. Argon clusters were used as the sputtering particles. The milling apparatus used in this embodiment has the ability to mill a processing object at a milling rate of 1.7 nm / min. when the processing object is quartz glass.

[0049] Referring to FIGS. 5(a) and 5(b), it was found that in the third embodiment, the polyimide was carbonized by irradiating the laser beam L1. Specifically, the composition ratio of carbon inside the film 21 increased to about 95% in the third embodiment, whereas it was about 80% in the second comparative example.

[0050] Also, in each of the second comparative example and the third embodiment, it was found that oxygen, which is an impurity, exists near the surface of the film. This oxygen is considered to be derived from water vapor (H2O) remaining in the chamber. Note that in XPS, hydrogen cannot be detected, so the composition ratio of hydrogen is omitted in FIG. 5.

[0051] Thus, it was found that polyimide can be carbonized by irradiating with the laser beam L1, and the composition ratio of carbon in the carbonized region 22 can be increased. On the other hand, even when the carbonized region 22 is formed using the laser beam L1 as in the third embodiment, it was found that an impurity gas (mainly water vapor) exists on the surface thereof. Therefore, in order to increase the purity of the generated carbon ions, as will be described later in the fourth embodiment and subsequent embodiments, it was found that it is preferable to adopt a configuration capable of removing the impurity gas while forming the carbonized region 22A.

[0052] Each of FIGS. 6(a) and 6(c) is an image showing the energy distribution of ions generated using the second comparative example and the third embodiment, respectively. The horizontal axis and the vertical axis of FIGS. 6(a) and 6(c) are 70 mm and 65 mm in full scale, respectively. Note that in the second comparative example, since the generation amount of carbon ions is small, the measurement results when the laser beam L2 is irradiated 20 shots are integrated and shown. Each of FIGS. 6(b) and 6(d) is a graph showing the energy spectrum of ions generated using the second comparative example and the third embodiment, respectively.

[0053] Referring to FIGS. 6(a) to 6(d), by irradiating the laser beam L2 during the period when the laser beam L1 is irradiated, the maximum energy of the carbon ions increased by approximately three times from approximately 4 MeV to approximately 10.7 MeV as compared with the case where only the laser beam L2 is irradiated. Also, by irradiating the laser beam L1 and the laser beam L2 simultaneously, it was found that the generation of hydrogen ions, which are impurity ions, can be suppressed while the generation amount of carbon ions increases.

[0054] 〔Second Embodiment〕 Regarding the film continuous feeding device 30 included in the carbon ion generation device 10A according to the second embodiment of the present invention, it will be described with reference to FIG. 7. FIG. 7(a) is a side view of the film continuous feeding device 30. FIG. 7(b) is a plan view of the head surface 351 in a modified example of the tape head 35 included in the film continuous feeding device 30. For convenience of explanation, members having the same functions as those described in the first embodiment are denoted by the same reference numerals, and their descriptions will not be repeated.

[0055] The carbon ion generation device 10 according to the first embodiment is configured to hold the film 21 having a square shape in a planar manner using a holding unit.

[0056] On the other hand, the carbon ion generation device 10A includes a film 21A formed in a tape shape and a film continuous feeding device 30 that continuously feeds the film 21A along its longitudinal direction, instead of the film 21 and the holding unit of the carbon ion generation device 10. The carbon ion generation device 10A further includes a control unit C. In the present embodiment, the film 21A, the film continuous feeding device 30, and the control unit C will be described.

[0057] <Film> The film 21A is formed in a tape shape. One end of the film 21A is fixed to a core that is a hollow cylinder. Moreover, the film 21A is wound around the core. The width of the film 21A is larger than the first region irradiated with the laser beam L1 and the second region irradiated with the laser beam L2.

[0058] Except for this point, the film 21A is configured in the same manner as the film 21. That is, the film 21A is made of a polyimide resin having a thickness of 5 μm. Note that the material constituting the film 21A is not limited to the polyimide resin, and the thickness is not limited to 5 μm.

[0059] <Film continuous feeding device> The film continuous feeding device 30 is disposed inside the chamber 11 as an alternative to the holding part of the carbon ion generating device 10. However, as will be described later, the film continuous feeding device 30 includes a holding part and a moving part.

[0060] As shown in Fig. 7(a), the film continuous feeding device 30 includes pulleys 311, 312, 321, 322, 331, 332, 341, 342, a tape head 35, motors 361, 362, and a base material 37.

[0061] (Base material) The base material 37 is a plate-like member made of metal (stainless steel in this embodiment), and the shapes of a pair of main surfaces are rectangular. On one main surface of the base material 37, pulleys 311, 312, 321, 322, 331, 332, 341, 342, a tape head 35, and motors 361, 362 and is are installed. Although not shown in Fig. 7, a stage capable of translating the position of the base material 37 along at least the z-axis direction may be provided below the base material 37.

[0062] (Pulley) The pulley 311 includes a rotatable rotating shaft. A core (hereinafter referred to as the first core) around which one end of the film 21A is wound is fixed to the rotating shaft. Therefore, the first core can rotate integrally with the pulley 311.

[0063] In this embodiment, the other end of the film 21A is fixed to a second core that is a hollow cylinder.

[0064] The pulley 312, similar to the pulley 311, includes a rotatable rotating shaft. A second core around which the other end of the film 21A is wound is fixed to the rotating shaft. Therefore, the core can 2 rotate integrally with the pulley 31

[0065] Each of the pulleys 321, 322, 331, 332, 341, 342 is provided between the pulley 311 and the pulley 312, and defines the path of the film 21A from the pulley 311 toward the pulley 312 (see Fig. 7(a)). Each of the pulleys 321, 322, 331, 332, 341, 342 also has a rotatable shaft configured to be rotatable, similar to the pulleys 311, 312.

[0066] In the present embodiment, the pulleys 311, 321, 331, 341 and the pulleys 312, 322, 332, 342 are provided to be mirror-symmetrical with a plane parallel to the zx plane shown in Fig. 7(a) as the symmetry plane.

[0067] The pulleys 311, 312, 321, 322, 331, 332, 341, 342 configured in this way can continuously send the film 21A along the arrow A from the pulley 311 toward the pulley 312. Therefore, the pulley 311 is an example of the first pulley that sends out the film 21A, and the pulley 312 is an example of the second pulley that winds up the film 21A.

[0068] (Tape head) The tape head 35 is a block-shaped member made of metal (stainless steel in this embodiment). The tape head 35 is formed into a decagon obtained by combining two hexagons of different sizes when viewed from the normal direction of the main surface of the base material 37 (see Fig. 7(a)). In the tape head 35, a pair of surfaces that are substantially parallel to the main surface of the base material 37 and are formed into a decagon as described above are referred to as a pair of main surfaces, and the surfaces that constitute the contours of the pair of main surfaces are referred to as outer surfaces.

[0069] The tape head 35 is positioned between the pulley 311 and the pulley 312 when viewed along the path of the film 21A. More specifically, for the tape head 35, the smaller of the two hexagons described above is positioned between the pulleys 341 and 342, and a part of the smaller hexagon is provided so as to protrude from the outer circumferential surface on the negative z-axis side among the outer circumferential surfaces circumscribing the pulleys 341 and 342. Therefore, the head surface 351, which is at least the end surface on the negative z-axis side of the outer surface of the tape head 35, contacts the film 21A in a state where the film 21A is pushed out in the negative z-axis direction from the outer circumferential surface on the negative z-axis side described above.

[0070] Note that the position of the tape head 35 can be adjusted in the direction of the arrow B parallel to the z-axis direction. Therefore, the amount by which the head surface 351 protrudes from the outer circumferential surface on the negative z-axis side described above can be arbitrarily adjusted for the tape head 35. In other words, the tape head 35 can determine its position in the normal direction (the z-axis direction in Fig. 7(a)) with respect to the main surface of the film 21A using the head surface 351. Therefore, the head surface 351 is an example of a holding portion that holds the film 21A in a planar shape at the beam spots P1 and P2.

[0071] A groove 352 is formed in the main surface on the side farther from the base material 37 (the main surface on the negative x-axis side) of the pair of main surfaces of the tape head 35. When viewed from the normal direction of the main surface of the base material 37, the groove 352 has a trapezoidal shape. Each of the pair of bottom sides of the groove 352 is located at the end side on the positive z-axis side and the end side on the negative z-axis side, respectively, of the contour of the tape head 35. That is, notches are formed in each of the end surface on the positive z-axis side and the head surface 351 of the outer surface of the tape head 35, and the groove 352 connects these notches.

[0072] The groove 352 extends from the end face on the +z-axis side of the outer surface of the tape head 35 to the head surface 351. The laser beam L1 is set such that its optical axis passes through the inside of the groove 352. Therefore, the laser beam L1 that has passed through the inside of the groove 352 is irradiated onto a partial region of the film 21A at the head surface 351.

[0073] Note that, similar to the case of the carbon ion generator 10, in the carbon ion generator 10A, the laser beam L2 is irradiated onto at least a partial region of the carbonized region 22A during the period when the laser beam L1 is irradiated (see (a) of FIG. 7).

[0074] In the present embodiment, both the first inclination angle and the second inclination angle are 0°. However, each of the first inclination angle and the second inclination angle is not limited to 0° and can be set as appropriate. Also, similar to the case of the carbon ion generator 10, in the carbon ion generator 10A, either forward-accelerated ions or backward-accelerated ions may be used as the carbon ions irradiated onto the tumor in heavy particle beam cancer treatment.

[0075] (Motor) In the present embodiment, the motors 361 and 362 are stepping motors. The motor 361 includes a rotatable rotating shaft. The rotating shaft of the motor 361 is mechanically coupled to the rotating shaft of the pulley 311. The motor 362 also has the same configuration as the motor 361, and the rotating shaft of the motor 362 is mechanically coupled to the rotating shaft of the pulley 312. Therefore, when the respective rotating shafts of the motors 361 and 362 rotate, the respective pulleys 311 and 312 are driven.

[0076] In the present embodiment, the motors 361 and 362 are controlled by the control unit C (see (a) of FIG. 7) of the carbon ion generator 10A. The control unit C drives the pulleys 311 and 312 by controlling the motors 361 and 362, and sends the film 21A from the pulley 311 to the pulley 312. The motors 361 and 362 and the pulleys 311 and 312 are an example of the moving part.

[0077] (Timing of irradiating light) In this embodiment, the control unit C stops the feeding of the film 21A (i.e., stops the motors 361 and 362), and then forms the carbonized region 22A by irradiating a part of the region of the film 21A with the laser beam L1. Then, while irradiating the carbonized region 22A with the laser beam L1, the laser beam L2 is irradiated to a part of the region of the carbonized region 22A. That is, the laser beam L1 and the laser beam L2 are simultaneously irradiated to the carbonized region 22A. According to this configuration, it is possible to sufficiently secure the time for carbonizing the polyimide resin contained in the region of the film 21A irradiated with the laser beam L1. However, each of the laser beam L1 and the laser beam L2 may be configured to irradiate the laser beam L2 after irradiating the laser beam L1 without simultaneous irradiation. In this regard, the carbon ion generator 10A is the same as the carbon ion generator 10.

[0078] Also, when the output of the laser beam L1 is sufficiently high and the polyimide resin constituting the film 21A can be quickly carbonized, the control unit C may be configured to irradiate the film 21A with the laser beam L1 and the laser beam L2 while feeding the film 21A (i.e., while driving the pulleys 311 and 312 using the motors 361 and 362).

[0079] In this case, as in the modified example shown in FIG. 7(b), the tape head 35 preferably has the length of the head surface 351 (the length along the direction of the arrow A) extended along the direction of the arrow A (the y-axis direction shown in FIG. 7(b)) in which the film 21A is fed. According to this configuration, within the plane of the head surface 351, the positions of the beam spot P1 (the region irradiated with the laser beam L1 in FIG. 7(b)) and the beam spot P2 (the region irradiated with the laser beam L2 in FIG. 7(b)) can be made different. a 。Furthermore, the motors 361 and 362 and the pulleys 311 and 312 continue to move the film 21A in the direction of arrow A so that the carbonized region 22A carbonized at the beam spot P1 overlaps with the position of the beam spot P2. As a result, the carbon ion generator 10A can generate carbon ions while feeding the film 21A.

[0080] <Control Unit> As described above, the control unit C controls the motors 361 and 362. Further, the control unit C controls the laser light source 12 that emits the laser beam L1 and the laser light source 15 that emits the laser beam L2.

[0081] The function of the control unit C can be realized by a program for causing a computer to function as the control unit C. In this case, the control unit C includes a computer having at least one control device (for example, a processor) and at least one storage device (for example, a memory) as hardware for executing the above program. By executing the above program by this control device and storage device, the control of the motors 361 and 362, the laser light source 12, and the laser light source 15 by the control unit C is realized.

[0082] 〔Third Embodiment〕 The film continuous feeding device 40 included in the carbon ion generator 10B according to the third embodiment of the present invention will be described with reference to FIG. 8. FIG. 8(a) is a plan view of the film continuous feeding device 40. FIG. 8(b) is a cross-sectional view of the rotary moving stage 41 included in the film continuous feeding device 40. For convenience of explanation, members having the same functions as the members described in the first and second embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0083] The film continuous feeding device 30 included in the carbon ion generator 10A according to the second embodiment is configured to continuously feed the tape-shaped film 21A along its longitudinal direction.

[0084] On the other hand, the film continuous feeding device 40 included in the carbon ion generation device 10B uses, for example, a film 21B formed in a circular shape instead of the film 21A, and rotates and moves the film 21B in the plane within the main surface of the film 21B (a plane parallel to the xy plane in FIG. 8(a)), thereby continuously feeding the film 21B. In the present embodiment, the film 21B and the film continuous feeding device 40 will be described.

[0085] <Film> The film 21B is formed in a circular shape in the present embodiment. However, the shape of the film 21B is not limited to a circular shape and can be appropriately determined. The film 21B may be, for example, a polygonal shape. In the present embodiment, the diameter of the film 21B is substantially the same as the outer diameter of the inner region of the stage body 4111 of the rotational movement stage 41 described later, and is larger than the first region irradiated with the laser beam L1 and the second region irradiated with the laser beam L2.

[0086] Except for this point, the film 21B is configured in the same manner as the film 21. That is, the film 21 B is made of a polyimide resin with a thickness of 5 μm. Note that the material constituting the film 21B is not limited to the polyimide resin, and the thickness is not limited to 5 μm.

[0087] <Film continuous feeding device> The film continuous feeding device 40 is disposed inside the chamber 11 as an alternative to the film continuous feeding device 30 in the carbon ion generation device 10A.

[0088] As shown in FIG. 8(a), the film continuous feeding device 40 includes a rotational movement stage 41 and a horizontal movement stage 42.

[0089] (Rotational movement stage) As shown in FIGS. 8(a) and 8(b), the rotary moving stage 41 includes a stage 411, a cross roller bearing 412, a fixture 413, a base material 414, a motor 415, a pulley 416, and a belt 417.

[0090] The stage 411 includes a stage body 4111 made of metal (stainless steel in this embodiment) and a back plate 4112. The stage body 4111 is a cylindrical member having a pair of bottom surfaces each provided with a circular opening and side surfaces interposed between the pair of bottom surfaces. Therefore, a through hole is formed in the region of the stage body 4111 including the central axis AC (see FIG. 8(b)).

[0091] In the stage body 4111, the vicinity of one of the pair of bottom surfaces (the bottom surface on the negative z-axis side shown in FIGS. 8(a) and 8(b)) is configured in a flange shape with a thicker side surface compared to the vicinity of the other bottom surface (the bottom surface on the positive z-axis side shown in FIGS. 8(a) and 8(b)). A groove 4113 is provided on the outer periphery of the flange-shaped portion. The belt 417 described later is hung on the groove 4113. In FIG. 8(b), the illustration of the belt 417 is omitted.

[0092] Also, in one bottom surface of the stage body 4111, an annular inner region located inside the groove 4113 has a surface that is dug in more than other regions of the one bottom surface. That is, a step is provided at the boundary between the inner region and other regions on one bottom surface. The film 21B formed in a circular shape substantially equal to the outer diameter of the inner region is fixed to the inner region using the fixture 413 described later.

[0093] The back plate 4112 is an annular plate-shaped member fixed to the other bottom surface of the stage body 4111. The inner ring of the cross roller bearing 412 is fitted in the vicinity of the other bottom surface of the stage body 4111. The back plate 4112 fixes the inner ring of the cross roller bearing 412 to the other bottom surface by sandwiching the cross roller bearing 412 together with the stage body 4111.

[0094] The fastener 413 is a plate-shaped member made of metal (stainless steel in this embodiment) and is in an annular shape. The outer diameter of the fastener 413 is slightly smaller than the outer diameter of the inner region of the stage body 4111, and its inner diameter is configured to be substantially the same as the diameter of the through hole of the stage 411. The fastener 413 is dropped into the inner region.

[0095] As shown in FIG. 8(b), the fastener 413 fixes the film 21B to the inner region by sandwiching the film 21B together with the stage body 4111. Although not shown in FIGS. 8(a) and 8(b), the fastener 413 is fixed to the stage 411 using mechanical fixing means. An example of the mechanical fixing means is a plurality of bolts. However, the mechanical fixing means is not limited to this and can be appropriately selected.

[0096] The base material 414 includes a base material body 4141 made of metal (stainless steel in this embodiment) and a back plate 4142 (see FIG. 8(b)). The base material body 4141 is a plate-shaped member in which the shapes of a pair of main surfaces are a combination of a rectangular shape and a circular shape (see FIG. 8(a)). When the main surface of the base material body 4141 is viewed in a plan view from the negative z-axis direction side, an opening concentric with the circular contour is provided in the circular region. The diameter of this opening exceeds the outer diameter of the other bottom surface of the stage body 4111 and is slightly smaller than the outer diameter (the diameter of the outer ring) of the cross roller ring 412. A portion including the other bottom surface of the stage body 4111 is fixed to this opening via the cross roller ring 412.

[0097] The back plate 4142 is an annular plate-shaped member fixed to the circular region of the base material body 4141. The outer ring of the cross roller ring 412 is fitted into the opening of the base material body 4141. The back plate 4142 fixes the outer ring of the cross roller ring 412 to the opening of the base material body 4141 by sandwiching the cross roller ring 412 together with the base material body 4141.

[0098] The cross roller bearing 412 is a type of roller bearing and is a bearing having an inner ring and an outer ring configured to be relatively rotatable. In the film continuous feeding device 40, the outer ring is fixed to the base material body 4141, and the stage body 4111 is fixed to the inner ring. Further, in the inner region of the stage body 4111, the film 21B is fixed so that the main surface of the film 21B is parallel to a pair of bottom surfaces of the stage body 4111. Therefore, the film continuous feeding device 40 rotates and moves the film 21B around the central axis AC as the rotation axis within the plane of the main surface of the film 21B (a plane parallel to the xy plane shown in Fig. 8(a)). Also, the stage body 4111 and the fastener 413 are an example of a holding portion that holds the film 21B in a planar shape at the beam spots P1 and P2. The stage body 4111 and the fastener 413 hold a plurality of locations on the outer edge of the film 21B by sandwiching the outer edge thereof.

[0099] In the rectangular region of the base material body 4141, a pulley 416 is provided on the main surface on the negative z-axis side. The pulley 416 has a rotatable rotation shaft. The rotation shaft of the pulley 416 is supported by the base material body 4141.

[0100] In the rectangular region of the base material body 4141, a motor 415 is fixed to the main surface on the positive z-axis side. In the present embodiment, the motor 415 is a stepping motor. The motor 415 has a rotatable rotation shaft. The rotation shaft of the motor 415 is mechanically coupled to the rotation shaft of the pulley 416. Therefore, when the rotation shaft of the motor 415 rotates, the pulley 416 also rotates.

[0101] The belt 417 is an annular member made of a resin having elasticity (rubber in the present embodiment). The belt 417 is hung on the outer edge portion of the pulley 416 and the groove 4113 of the stage 411. Note that the length of the belt 417 is the above-mentioned outer edge portion and the groove 411 3It is determined such that appropriate tension is applied in the state of being wound around. The belt 417 transmits the driving force of the motor 415 to the stage 411. Therefore, when the belt 417 is sent in the direction of arrow A by the rotation of the pulley 416, the stage 411 rotates in the direction of arrow B (see Fig. 8(a)).

[0102] In addition, an additional pulley may be provided on the main surface on the negative z-axis side of the base material body 4141 between the pulley 416 and the stage 411. In this case, the additional pulley is provided at a position where it slightly meanders the path of the belt 417. Further, the additional pulley is configured to be able to adjust the meandering state of the belt 417. In the film continuous feeding device 40, by adjusting the meandering state using the additional pulley, the tension of the belt 417 can be adjusted, and as a result, the degree of friction generated between the belt 417 and each of the pulley 416 and the stage 411 can be adjusted.

[0103] In the present embodiment, the motor 415 is controlled by the control unit C (see Fig. 8(a)) of the carbon ion generation device 10B. The control unit C rotates the stage 411 of the rotational movement stage 41 via the pulley 416 and the belt 417 by controlling the motor 415. In other words, the control unit C rotates and moves the film 21B in the in-plane direction on the main surface of the film 21B (the in-plane direction of a plane parallel to the xy plane shown in Fig. 8(a)). Therefore, the stage 411 of the rotational movement stage 41, the cross roller ring 412, the motor 415, the pulley 416, and the belt 417 are an example of the moving part. Note that the control unit C of the carbon ion generation device 10B may be configured in the same manner as the control unit C of the carbon ion generation device 10A, and thus the description thereof is omitted in the present embodiment.

[0104] In the carbon ion generation device 10 (see Fig. 1), the laser beam L1 and the laser beam L2 are each irradiated onto the film 21 from different main surface sides of the film 21. In this regard, the carbon ion generation device 10A (see Fig. 7) is the same as the carbon ion generation device 10.

[0105] On the other hand, in the carbon ion generation device 10B, each of the laser beam L1 and the laser beam L2 is irradiated onto the film 21B from the same main surface side of the film 21B (the negative z-axis side in FIG. 8(a)).

[0106] Thus, in one aspect of the present invention, each of the laser beam L1 and the laser beam L2 can be irradiated onto the film from different main surface sides of the film, or can be irradiated onto the film from the same main surface side of the film.

[0107] Note that, also in the carbon ion generation device 10B, similar to the cases of the carbon ion generation devices 10 and 10A, the laser beam L2 is irradiated onto at least a part of the carbonized region 22B during the period when the laser beam L1 is irradiated (see FIG. 8(a)).

[0108] Also, in the carbon ion generation device 10B, each of the first inclination angle and the second inclination angle can be set as appropriate. Also, similar to the case of the carbon ion generation device 10, in heavy particle beam cancer treatment, either forward-accelerated ions or backward-accelerated ions can be used as the carbon ions irradiated onto the tumor. In the film continuous feeding device 40, since a through-hole is formed in the stage 411, not only backward-accelerated ions but also forward-accelerated ions can be used.

[0109] (Timing of irradiating light) In this embodiment, the control unit C stops the feeding of the film 21B (i.e., stops the motor 415), and then forms the carbonized region 22B by irradiating a part of the region of the film 21B with the laser beam L1. Then, while irradiating the carbonized region 22B with the laser beam L1, the control unit C irradiates at least a part of the carbonized region 22B with the laser beam L2. That is, the laser beam L1 and the laser beam L2 are simultaneously irradiated on the carbonized region 22B. According to this configuration, it is possible to sufficiently secure the time for carbonizing the polyimide resin contained in the region of the film 21B irradiated with the laser beam L1. However, each of the laser beam L1 and the laser beam L2 may be configured to irradiate the laser beam L2 after irradiating the laser beam L1, instead of irradiating simultaneously.

[0110] Also, when the output of the laser beam L1 is sufficiently high and the polyimide resin constituting the film 21B can be quickly carbonized, the control unit C may be configured to irradiate the film 21B with the laser beam L1 and the laser beam L2 while feeding the film 21B (i.e., while rotating the rotation moving stage 41 using the motor 415). In this case, on the main surface of the stage 411 where the film 21B is fixed, the positions of the region irradiated with the laser beam L1 and the region irradiated with the laser beam L2 may be different.

[0111] In these aspects, the carbon ion generator 10B is the same as the carbon ion generators 10 and 10A.

[0112] (Horizontal moving stage) As shown in Fig. 8(a), the horizontal movement stage 42 includes a base material 421 and a stage 422. The horizontal movement stage 42 can translate the position of the stage 422, which is provided upright perpendicular to the base material 421, within the plane of the main surface of the base material 421 (a plane parallel to the zx plane shown in Fig. 8(a)). That is, the horizontal movement stage 42 can move the position of the stage 422 along each of the x-axis direction and the z-axis direction. As the horizontal movement stage 42, a precision stage used when assembling an optical system can be adopted, and a precision stage capable of translating the stage within a plane can be used.

[0113] In the present embodiment, the position of the stage 422 is controlled by the control unit C of the carbon ion generator 10B. The control unit C translates the rotary movement stage 41 fixed on the stage 422 within a plane. Therefore, the horizontal movement stage 42 is an example of a moving part.

[0114] As described above, by the horizontal movement stage 42 translating the rotary movement stage 41, the carbon ion generator 10B can arbitrarily change the radius R, which is the distance between the region irradiated with the laser beam L1 and the laser beam L2 and the central axis AC of the stage main body 4111, without scanning each of the laser beam L1 and the laser beam L2.

[0115] In the present embodiment, as shown in Fig. 8(a), in a state where the horizontal movement stage 42 is fixed (i.e., the radius R is constant), the step of generating carbon ions and the step of rotating the stage 411 of the rotary movement stage 41 by a predetermined angle are alternately performed. As a result, a plurality of carbonized regions 22B are discontinuously formed on the circumference of a circle on the film 21B.

[0116] However, as described above, when the output of the laser beam L1 is sufficiently high and the polyimide resin constituting the film 21B can be quickly carbonized, a step of generating carbon ions while feeding the film 21B by rotating the stage 411 may be performed. In this case, an annular carbonized region 22B is formed in the film 21B. Further, a step of generating carbon ions while feeding the film 21B may be performed by rotating the stage 411 while translating the stage 422 along the x-axis direction. In this case, a spiral carbonized region 22B is formed in the film 21B.

[0117] 〔Fourth Embodiment〕 The film continuous feeding device 30C included in the carbon ion generation device 10C according to the fourth embodiment of the present invention and the laser beam L1 used in the carbon ion generation device 10C will be described with reference to FIG. 9. FIG. 9(a) is a side view of the film continuous feeding device 30C. FIG. 9(b) is a plan view of the head surface 351C of the tape head 35C included in the film continuous feeding device 30C. The carbon ion generation device 10C can also be said to be a modified example of the carbon ion generation device 10A shown in FIGS. 2(a) and 2(b). For the sake of convenience of explanation, members having the same functions as those described in the first and second embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0118] The carbon ion generation device 10A according to the second embodiment is configured to generate a carbonized region 22A in a part of the film 21A by heating the film 21A using a single laser beam L1.

[0119] On the one hand, the carbon ion generator 10C constitutes the laser beam L1 with three sub-laser beams L11, L12, and L13. Each of the beam spots P11, P12, and P13, which are the irradiation regions of the sub-laser beams L11, L12, and L13 on the film 21C, is provided along the feeding direction of the film 21C (the direction of the arrow A shown in Fig. 9(b)). Therefore, the first laser irradiation mechanism of the carbon ion generator 10C includes three laser light sources that respectively emit the sub-laser beams L11, L12, and L13. Each of these three laser light sources is configured in the same manner as the laser light source 12 shown in Fig. 1(a) and Fig. 7(a). In the tape head 35C, in order to provide each of the beam spots P11, P12, and P13 along the feeding direction of the film 21C, the width of the groove 352C provided in the tape head 35C in the feeding direction is wider than the groove 352 of the tape head 35 shown in Fig. 7(a).

[0120] In the carbon ion generator 10C, the power density of each of the sub-laser beams L11, L12, and L13 at each of the beam spots P11, P12, and P13 is determined to increase from the front stage to the rear stage when viewed along the feeding direction of the film 21C (that is, the direction of the arrow A shown in Fig. 9(b)).

[0121] According to this configuration, the temperature of the carbonized region 22C at each of the beam spots P11, P12, and P13 can be increased step by step from the front stage to the rear stage. For example, the power of the sub-laser beam L11 and the spot diameter of the beam spot P11 can be set so that the temperature of the carbonized region 22C at the beam spot P11 becomes 600 °C, the power of the sub-laser beam L12 and the spot diameter of the beam spot P12 can be set so that the temperature of the carbonized region 22C at the beam spot P12 becomes 800 °C, and the power of the sub-laser beam L13 and the spot diameter of the beam spot P13 can be set so that the temperature of the carbonized region 22C at the beam spot P13 becomes 1000 °C.

[0122] However, the temperatures of the carbonized regions 22C at each of the beam spots P11, P12, and P13 are not limited to 600°C, 800°C, and 1000°C. The temperature of the carbonized region 22C at the beam spot P11 may be set to a temperature at which at least a part of the film 21C is carbonized (for example, 500°C or higher). Also, the temperature of the carbonized region 22C at the beam spot P12 may be set higher than the temperature of the carbonized region 22C at the beam spot P11 and in a temperature range less than the melting point of carbon (for example, about 4000K when carbon is graphite). Further, the temperature of the carbonized region 22C at the beam spot P13 may be set higher than the temperature of the carbonized region 22C at the beam spot P12 and in a temperature range less than the melting point of carbon (for example, about 4000K when carbon is graphite).

[0123] Also, in the carbon ion generator 10C, the power densities of the respective sub-laser beams L11, L12, and L13 at each of the beam spots P11, P12, and P13 may be determined to be equal.

[0124] Also, in the present embodiment, the beam spot P2, which is the irradiation region of the laser beam L2 on the film 21C, is set to be included in the beam spot P13 (see (b) of FIG. 9). According to this configuration, during the period when the laser beam L13 is irradiated on the carbonized region 22C, the laser beam L2 can be irradiated onto the beam spot P13 of the laser beam L13. However, the beam spot P2 may be set to be located further downstream than the beam spot P13. In this case, in order to suppress the attachment of impurity gas to the carbonized region 22C after the laser beam L13 is irradiated, the distance between the beam spot P13 and the beam spot P2 is preferably as short as possible.

[0125] 〔Fifth Embodiment〕 The film continuous feeding device 30C included in the carbon ion generation device 10D according to the fifth embodiment of the present invention and the laser beam L1 used in the carbon ion generation device 10D will be described with reference to FIG. 10. FIG. 10(a) is a side view of the film continuous feeding device 30C. FIG. 10(b) is a plan view of the head surface 351C of the tape head 35C included in the film continuous feeding device 30C. The carbon ion generation device 10 D can also be said to be a modified example of the carbon ion generation device 10A shown in FIGS. 2(a) and 2(b). For the sake of convenience of explanation, members having the same functions as those described in the first and second embodiments are denoted by the same reference numerals, and their descriptions will not be repeated.

[0126] In the carbon ion generation device 10A according to the second embodiment, the first laser irradiation mechanism is configured such that the shape of the beam spot P1, which is the irradiation region of the laser beam L1 on the film 21A, is circular.

[0127] On the other hand, in the carbon ion generation device 10D, the first laser irradiation mechanism is configured such that the shape of the beam spot P1D, which is the irradiation region of the laser beam L1 on the film 21C, is an oval shape in which the major axis is parallel to the feeding direction of the film 21C and the minor axis is parallel to the width direction of the film 21C (see FIGS. 10(a) and 10(b)). That is, in the carbon ion generation device 10D, the beam spot P1D is configured such that the length in the feeding direction of the film 21C is longer than the direction orthogonal to the feeding direction.

[0128] Further, in the present embodiment, the beam spot P2, which is the irradiation region of the laser beam L2 on the film 21C, is set to be included in the beam spot P1D having an oval shape (see (b) of FIG. 10). According to this configuration, the laser beam L2 can be irradiated onto the beam spot P1D of the laser beam L1 while the laser beam L1 is being irradiated onto the carbonized region 22C. Further, in this case, it is preferable that the beam spot P2 is provided as far as possible on the rear stage side (negative y-axis direction) within the range of the beam spot P1D. According to this configuration, the laser beam L2 can be irradiated onto the carbonized region 22C that has been irradiated with the laser beam L1 for a long time.

[0129] However, the beam spot P2 may be set to be located further on the rear stage than the range of the beam spot P1D. In this case, in order to suppress the adhesion of the impurity gas to the carbonized region 22C after the laser beam L1 is irradiated, it is preferable that the shortest distance between the beam spot P1D and the beam spot P2 is as short as possible.

[0130] 〔Sixth Embodiment〕 The film continuous feeding device 30C and the galvanometer mirror 14D included in the carbon ion generation device 10E according to the sixth embodiment of the present invention, and the laser beam L1 used in the carbon ion generation device 10E will be described with reference to FIG. 11. FIG. 11 is a side view of the film continuous feeding device 30C. The carbon ion generation device 10E can also be said to be a modified example of the carbon ion generation device 10C shown in FIGS. 9(a) and 9(b). For the sake of convenience of explanation, members having the same functions as the members described in the first and second embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0131] The film continuous feeding device 30C included in the carbon ion generation device 10E is configured in the same manner as the film continuous feeding device 30C included in the carbon ion generation device 10C. Therefore, in the carbon ion generation device 10E, the width of the groove 352C provided in the tape head 35C in the feeding direction is wider than the groove 352 of the tape head 35 shown in FIG. 7(a).

[0132] In the carbon ion generation device 10E, the galvanometer mirror 14D that forms part of the first laser irradiation mechanism is provided in place of the mirror 14 of the carbon ion generation device 10 shown in FIG. 1. The galvanometer mirror 14D is an example of a scanning mirror and is also called a galvanometer scanner. The galvanometer mirror 14D periodically scans the laser beam L1 incident on the reflecting surface along the feeding direction of the film 21C (the direction of arrow A shown in FIG. 11) by slightly vibrating the reflecting surface around the axis of rotation. In the present embodiment, the irradiation region of the laser beam L1 scanned by the galvanometer mirror 14D is set to be the same as the beam spot P1D shown in FIG. 10(b).

[0133] Here, when the laser beam L1 scanned by the galvanometer mirror 14D is scanned in the same direction as the feeding direction of the film 21C, it is preferably synchronized with the feeding speed of the film 21C. The control unit C shown in FIG. 11 controls the vibration frequency and rotation angle of the reflecting surface of the galvanometer mirror 14D so that the laser beam L1 scanned in the same direction as the feeding direction of the film 21C is synchronized with the feeding speed of the film 21C.

[0134] According to this configuration, when the laser beam L1 is scanned in the same direction as the feeding direction of the film 21C, the laser beam L1 and the film 21C move synchronously. Therefore, compared with the case where the single laser beam L1 is not scanned (for example, in the case of the carbon ion generation device 10A shown in FIG. 7), the time for irradiating the carbonization region 22C with the laser beam L1 can be lengthened without stopping the feeding of the film 21C. Therefore, even without stopping the feeding of the film 21C, sufficient time can be ensured for carbonizing the polyimide resin contained in the region of the film 21C irradiated with the laser beam L1.

[0135] Further, in the carbon ion generator 10E, it is preferable that the power density in the irradiation region formed by the laser beam L1 on the film 21C is determined to continuously increase from the front stage to the rear stage when viewed along the feeding direction of the film 21C. In the present embodiment, the control unit C sets the power of the laser beam L1 such that (1) when the irradiation region is located at the most front stage, the temperature of the irradiation region becomes 600°C, (2) when the irradiation region is located at the most rear stage, the temperature of the irradiation region becomes 1000°C, and (3) controls the laser light source 12 so that the power of the laser beam L1 continuously increases from the front stage to the rear stage.

[0136] However, in the carbon ion generator 10E, the power density in the irradiation region formed by the laser beam L1 on the film 21C can also be determined to increase stepwise from the front stage to the rear stage when viewed along the feeding direction of the film 21C. Note that the number of steps for increasing the power density is not limited and can be determined as appropriate. For example, it may be two steps, three steps, or eight steps.

[0137] Also, in the present embodiment, the beam spot, which is the irradiation region of the laser beam L2 on the film 21C, is provided at the same position as the beam spot P2 shown in FIG. 10(b). Since the control unit C controls the laser light source 15 so that the laser beam L2 irradiates the film 21C when the laser beam L1, which is scanned in synchronization with the feeding speed of the film 21C, reaches the end on the negative y-axis side of the scanning range, when the laser beam L2 irradiates the film 21C, the irradiation region of the laser beam L2 is included in the irradiation region of the laser beam L1 (refer to the laser beam L1 located most on the negative y-axis side among the three laser beams L1 shown in FIG. 11). According to this configuration, during the period when the laser beam L1 irradiates the carbonized region 22C, the laser beam L2 can be irradiated onto the irradiation region of the laser beam L1. However, the irradiation region of the laser beam L2 may be set to be located further downstream than the range where the irradiation region of the scanned laser beam L1 moves. In this case, in order to suppress the adhesion of impurity gas to the carbonized region 22C after the laser beam L1 is irradiated, it is preferable that the shortest distance between the irradiation region of the laser beam L1 and the irradiation region of the laser beam L2 is as short as possible.

[0138] 〔Summary〕 The carbon ion generation device according to the first aspect of the present invention irradiates a part of a film made of an organic compound with a first laser beam to carbonize the part, in-situ a first laser irradiation mechanism for generating a carbonized region, and a second laser irradiation mechanism for generating carbon ions from the carbonized region by irradiating at least a part of the carbonized region with a second laser beam.

[0139] According to the above configuration, when a carbonized region is generated by irradiating a part of the film with the first laser beam, the impurity layers formed on the front surface and the back surface near the carbonized region are removed. Therefore, according to the first aspect, in a carbon ion generation device using a laser-driven ion acceleration method, the generation of impurity ions can be suppressed.

[0140] In addition, the carbon ion generation device according to the second aspect of the present invention, in addition to the configuration of the carbon ion generation device according to the first aspect described above, the wavelength and output of the first laser beam, and the area of the region on the film irradiated with the first laser beam are determined so as to heat the temperature of the film in the region to 600°C or higher, and the configuration is adopted.

[0141] According to the above configuration, by irradiating the first laser beam, while generating a carbonized region in a part of the film, the impurity layers formed on the front surface and the back surface in the vicinity of the carbonized region can be removed. Therefore, according to the second aspect, the generation of impurity ions can be reliably suppressed, and the purity of the generated carbon ions can be increased.

[0142] In addition, the carbon ion generation device according to the third aspect of the present invention, in addition to the configuration of the carbon ion generation device according to the first aspect or the second aspect described above, further includes a holding unit that holds the film so that at least the region irradiated with the first laser beam and the region irradiated with the second laser beam are planar, and a moving unit that moves the film, and the film is larger than the region irradiated with the first laser beam and the region irradiated with the second laser beam, and the configuration is adopted.

[0143] According to the above configuration, by relatively moving the positions of the regions irradiated with the first laser beam and the second laser beam on the film, carbon ions can be continuously generated a plurality of times while using one film. Therefore, according to the third aspect, the film replacement cycle can be extended.

[0144] Further, the carbon ion generator according to the fourth aspect of the present invention, in addition to the configuration of the carbon ion generator according to the third aspect described above, the film is formed in a tape shape, and the moving unit includes a first pulley that feeds out the film and a second pulley that winds up the film, and the holding unit is provided between the first pulley and the second pulley and includes a tape head that determines the position in the normal direction to the main surface of the film. This configuration is adopted.

[0145] According to the above configuration, the moving unit can move the position of the film along a predetermined direction. Therefore, according to the fourth aspect, by moving the film, carbon ions can be continuously generated a plurality of times without moving the region irradiated with the first laser light and the region irradiated with the second laser.

[0146] Further, in the carbon ion generator according to the fifth aspect of the present invention, in addition to the configuration of the carbon ion generator according to the fourth aspect described above, the first laser irradiation mechanism further includes a plurality of laser light sources that each emit each of the plurality of sub-laser lights that constitute the first laser light, and each of the irradiation regions of the sub-laser lights on the film is provided along the feeding direction of the film. This configuration is adopted.

[0147] According to the above configuration, since irradiation regions can be provided at a plurality of locations on the fed film, the integration time during which the first laser light can be irradiated onto the carbonized region without stopping the feeding of the tape can be made longer. Therefore, the impurity gas adhering to the surface of the carbonized region can be removed, so that the generation of impurity ions can be reliably suppressed and the purity of the generated carbon ions can be increased.

[0148] Further, in the carbon ion generation device according to the sixth aspect of the present invention, in addition to the configuration of the carbon ion generation device according to the fifth aspect described above, the power density of the sub-laser light in each of the irradiation regions is determined to increase from the front stage to the rear stage when viewed along the feeding direction. Such a configuration is adopted.

[0149] The higher the power density of the first laser light, the higher the temperature of the carbonization region can be raised. Therefore, the impurity gas adhering to the surface of the carbonization region can be further removed. However, if the first laser light having a high power density sufficient to sufficiently remove the impurity gas is suddenly irradiated on the film, the carbonization region may be damaged due to the rapid change from the organic compound to carbon. According to the above configuration, after setting a plurality of irradiation regions, the power density of the sub-laser light in each irradiation region can be increased step by step. Therefore, it is possible to increase the purity of the generated carbon ions while reducing the possibility of damage to the carbonization region.

[0150] Further, in the carbon ion generation device according to the seventh aspect of the present invention, in addition to the configuration of the carbon ion generation device according to the 4 above aspect, the irradiation region of the first laser light on the film has a configuration in which the length in the feeding direction of the film is longer than the length in the direction orthogonal to the feeding direction.

[0151] According to the above configuration, the integration time during which the first laser light can be irradiated on the carbonization region without stopping the feeding of the tape can be made longer. Therefore, the impurity gas adhering to the surface of the carbonization region can be removed, so that the generation of impurity ions can be reliably suppressed and the purity of the generated carbon ions can be increased.

[0152] The carbon ion generator according to the eighth aspect of the present invention, in addition to the configuration of the carbon ion generator according to the fourth aspect described above, the first laser irradiation mechanism further includes a scanning mirror that scans the first laser light along the film feeding direction and in synchronization with the film feeding speed.

[0153] According to the above configuration, it is possible to increase the integration time during which the first laser light can be irradiated onto the carbonized region without stopping the tape feeding. Therefore, since the impurity gas adhering to the surface of the carbonized region can be removed, the generation of impurity ions can be reliably suppressed, and the purity of the generated carbon ions can be increased.

[0154] In the carbon ion generator according to the ninth aspect of the present invention, in addition to the configuration of the carbon ion generator according to the eighth aspect described above, the power density in the irradiation region formed by the first laser light on the film is determined to be gradually or continuously increased from the front stage to the rear stage when viewed along the feeding direction.

[0155] According to the above configuration, since the first laser light can be scanned in synchronization with the film feeding direction and the feeding speed, and the power density of the first laser light can be gradually or continuously increased, it is possible to increase the purity of the generated carbon ions while reducing the possibility of damage to the carbonized region.

[0156] Further, the carbon ion generator according to the tenth aspect of the present invention, in addition to the configuration of the carbon ion generator according to the third aspect described above, the film is formed in a circular shape or a polygonal shape, the holding portion holds a plurality of locations on the outer edge of the film, and the moving portion moves the holding portion along the in-plane direction on the main surface of the film.

[0157] According to the above configuration, the moving portion can move the position of the film along the in-plane direction of the film. Therefore, the first 10According to an aspect, by moving the film, carbon ions can be continuously generated multiple times without moving the region irradiated with the first laser light and the region irradiated with the second laser.

[0158] Further, the carbon ion generation device according to the eleventh aspect of the present invention, in addition to the configuration of the carbon ion generation device according to any one of the first aspect to the tenth aspect described above, the second laser irradiation mechanism irradiates the second laser light during the period when the first laser irradiation mechanism irradiates the first laser light.

[0159] According to the above configuration, after irradiating the first laser light, it is possible to prevent the impurity layer from being formed again on the front surface and the back surface near the carbonized region. Therefore, according to the 11 aspect, the generation of impurity ions can be further suppressed, and the purity of the generated carbon ions can be further increased.

[0160] Further, the carbon ion generation device according to the twelfth aspect of the present invention, in addition to the configuration of the carbon ion generation device according to any one of the third aspect to the tenth aspect described above, in the film, the region irradiated with the first laser light and the region irradiated with the second laser light are different in position, and the moving unit moves the film so that the carbonized region generated by irradiating the first laser light overlaps with the region irradiated with the second laser light.

[0161] According to the above configuration, the carbonized region generated in the region irradiated with the first laser light is sequentially moved to the region irradiated with the second laser light, and then carbon ions are generated. Therefore, since the generation of the carbonized region and the generation of carbon ions from the carbonized region can be carried out in parallel, according to the 12 aspect, the repetition frequency of generating carbon ions can be increased.

[0162] In addition, the carbon ion generator according to the 13th aspect of the present invention, in addition to the configuration of the carbon ion generator according to any one of the above-described 1st to 12th aspects, the thickness of the film is 12.5 μm or less.

[0163] When the second laser light is irradiated on one surface of the film (for example, referred to as the front surface), the electrons excited by the second laser light in the film travel toward the other surface of the film (for example, referred to as the back surface) while diffusing in the film. Therefore, the thicker the film, the larger the region where the polarization electric field is formed (that is, the region where carbon ions are generated) on the back surface of the film. The fact that the region where the polarization electric field is formed becomes larger means that the intensity of the polarization electric field becomes lower due to the lower electron density in the region. Since there is a positive correlation between the intensity of the polarization electric field and the acceleration energy of the generated carbon ions, it is preferable that the intensity of the polarization electric field is high in order to generate the acceleration energy of carbon ions having a high acceleration energy. According to the above configuration, carbon ions with a maximum acceleration energy of 8.5 MeV can be generated.

[0164] In addition, in order to control the generated carbon ions in the subsequent stage, it is preferable that the region where the carbon ions are generated is small. According to the above configuration, it is possible to prevent the region where the carbon ions are generated from becoming too large, so that the control of the carbon ions in the subsequent stage becomes easy.

[0165] In addition, the carbon ion generator according to the 14th aspect of the present invention, in addition to the configuration of the carbon ion generator according to any one of the above-described 1st to 13th aspects, the film is made of a polyimide resin.

[0166] Polyimide resin films are easily available and have sufficiently high mechanical strength. Therefore, polyimide resin is suitable as a material for forming the film. Also, polyimide resin films of various thicknesses are on the market, and even those as thin as about 5 μm can be stably obtained. In this regard as well, polyimide resin is suitable as a material for forming the film.

[0167] 〔Supplementary Notes〕 The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope indicated in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Explanation of Reference Numerals

[0168] 10, 10A, 10B Carbon ion generator 12 Laser light source (first laser light source) L1 Laser light (first laser light) 15 Laser light source (second laser light source) L2 Laser light (second laser light) 21, 21A, 21B Film 22, 22A, 22B Carbonized region P1 Beam spot (region irradiated with the first laser light) P2 Beam spot (region irradiated with the second laser light) P3 Ion generation region 30, 40 Film continuous feeding device 311, 312 Pulley (first pulley, second pulley, part of the moving part) 35 Tape head 351 Head surface 361, 362 Motor (part of the moving part) 41 Rotary moving stage 411 Stage (part of the moving part) 4111 Stage body 4112 Back plate 412 Cross roller (part of the moving part) 413 Fastener 414 Base material 4141 Base material body 4142 Back plate 415 Motor (part of the moving part) 416 Pulley (part of the moving part) 417 Belt (part of the moving part) 42 Horizontal moving stage (part of the moving part) 421 Base material 422 Stage

Claims

1. A first laser irradiation mechanism that carbonizes a part of a film made of an organic compound by irradiating the part with a first laser beam to generate a carbonized region; A second laser irradiation mechanism that generates carbon ions from the carbonized region by irradiating at least a part of the carbonized region with a second laser beam; A carbon ion generation device, characterized by the above.

2. The wavelength and output of the first laser beam, and the area of the region of the film irradiated with the first laser beam are determined so as to heat the temperature of the film in the region to 600°C or higher. The carbon ion generation device according to claim 1, characterized by the above.

3. A holding part that holds the film so that at least the region irradiated with the first laser beam and the region irradiated with the second laser beam are planar; A moving part that moves the film; The carbon ion generation device further includes the above. The film is larger than the region irradiated with the first laser beam and the region irradiated with the second laser beam. The carbon ion generation device according to claim 1 or 2, characterized by the above.

4. The film is formed in a tape shape. The moving part includes a first pulley that feeds out the film and a second pulley that winds up the film. The holding part is provided between the first pulley and the second pulley, and includes a tape head that determines the position in the normal direction to the main surface of the film. The carbon ion generation device according to claim 3, characterized by the above.

5. The first laser irradiation mechanism further includes a plurality of laser light sources that each emit each of a plurality of sub-laser beams that constitute the first laser beam. Each of the irradiation regions of the sub-laser light on the film is provided along the feeding direction of the film. The carbon ion generation device according to claim 4, characterized in that.

6. The power density of the sub-laser light in each of the irradiation regions is determined to increase from the front stage to the rear stage when viewed along the feeding direction. The carbon ion generation device according to claim 5, characterized in that.

7. The irradiation region of the first laser light on the film has a length in the feeding direction of the film that is longer than the length in the direction orthogonal to the feeding direction. The carbon ion generation device according to claim 4, characterized in that.

8. The first laser irradiation mechanism further includes a scanning mirror that scans the first laser light along the feeding direction of the film and in synchronization with the feeding speed of the film. The carbon ion generation device according to claim 4, characterized in that.

9. The power density in the irradiation region formed by the first laser light on the film is determined to increase stepwise or continuously from the front stage to the rear stage when viewed along the feeding direction. The carbon ion generation device according to claim 8, characterized in that.

10. The film is formed into a circular shape or a polygonal shape. The holding part holds a plurality of locations on the outer edge of the film. The moving part moves the holding part along the in-plane direction on the main surface of the film. The carbon ion generation device according to claim 3, characterized in that.

11. The second laser irradiation mechanism irradiates the second laser light during the period when the first laser irradiation mechanism irradiates the first laser light. The carbon ion generation device according to any one of claims 1 to 10, characterized in that...

12. In the film, the region irradiated with the first laser beam and the region irradiated with the second laser beam are different in position. The moving unit moves the film so that the carbonized region generated by irradiation with the first laser beam overlaps with the region irradiated with the second laser beam. The carbon ion generation device according to any one of claims 3 to 10, characterized in that...

13. The thickness of the film is 12.5 μm or less. The carbon ion generation device according to any one of claims 1 to 12, characterized in that...

14. The film is made of a polyimide resin. The carbon ion generation device according to any one of claims 1 to 13, characterized in that...

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