Cyclotron and method for operating the cyclotron

Abstract

To provide a cyclotron and a method for operating the cyclotron.SOLUTION: A cyclotron comprises: rotatable pieces 12 for generating a magnetic field in a particle acceleration chamber 14; and an upper part 101 and lower part 102 of the particle acceleration chamber 14 configured to be separable from each other. Therein: the rotatable pieces 12 each are at least partially made of a permanent magnet material, each are oriented along respective axis 18 such that an extremity of the rotatable pieces 12 is closer to a central axis 11 of the cyclotron than another extremity, and each are rotatable about the respective axis 18; the magnetic field generated by the rotatable pieces 12 varies depending on positions of the rotatable pieces 12 about the respective axes 18; and the rotatable pieces each have a cross-section situated closer to the central axis 11 of the cyclotron which is smaller than other cross-sections which are situated farther from the central axis 11 of the cyclotron; and the cross-sections of the rotatable pieces 12 are transverse to the respective axes 18.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cyclotron and a method for operating a cyclotron. [Background technology]

[0002] In a modern cyclotron, the magnetic circuit consists of two symmetrical poles located on either side of the median plane and separated by a gap through which the accelerated particles circulate. The magnetic circuit is completed by a magnetic flux return to close the circuit and a yoke that acts as a base plate for the poles. The poles are surrounded by a pair of induction coils traversed by a current, which generate a uniform and constant magnetic field capable of confining the particles according to an essentially circular or, more precisely, a spiral-shaped trajectory in the median plane.

[0003] Machines with azimuthal magnetic field variations have also been designed. The poles of the electromagnet are then divided into sectors with alternating small and larger gaps.

[0004] The excitation of the magnets used in cyclotrons requires high power. In view of the development of more environmentally friendly cyclotrons, there is interest in producing cyclotrons that offer low energy consumption.

[0005] US Pat. No. 7,466,085 describes a cyclotron consisting of a plurality of dees and a plurality of permanent magnets arranged alternately in a circular array, each de?ning a channel through Which ions travel.

[0006] Although attempts have been made to provide permanent magnet cyclotrons, there remains a need for a cyclotron that allows for the optimization of a variable magnetic field for a given cyclotron footprint. Summary of the Invention

[0007] The object of the present invention is to provide a cyclotron comprising a particle acceleration chamber, a rotatable part for generating a magnetic field in the particle acceleration chamber, an upper part above the particle acceleration chamber and a lower part below the particle acceleration chamber, the upper part and the lower part being configured to be separable from each other, wherein at least a part of the rotatable part: each formed at least in part from a permanent magnetic material; each extending along a respective axis, the respective axes being oriented such that an end of the rotatable element is closer to the central axis of the cyclotron than the other end; each rotatable about their respective axes between several positions, and the magnetic field generated by the rotatable parts within the chamber is a function of the position of the rotatable parts about their respective axes; and each having a cross section located near the central axis of the cyclotron that is smaller than the other cross sections located further from the central axis of the cyclotron, the cross sections of the rotatable parts being transverse to their respective axes.

[0008] According to one embodiment, the cross section of the rotatable components decreases along their respective axes towards the ends of the rotatable components closer to the central axis.

[0009] According to one embodiment, the rotatable part has a frusto-conical shape, the cross section of the rotatable part decreasing towards the end of the rotatable part closer to the central axis.

[0010] According to one embodiment, the cyclotron further comprises a return yoke surrounding the particle acceleration chamber, the rotatable part being within the return yoke.

[0011] According to one embodiment, the particle acceleration chamber follows a median plane and the axes of each of the rotatable parts are oriented obliquely towards or parallel to the median plane.

[0012] According to one embodiment, the axes of each of the rotatable parts are oriented towards the central axis.

[0013] According to one embodiment, the rotatable parts each comprise a stack of permanent magnet plates fixed to one another, the plates located closer to the central axis of the cyclotron having a surface with a smaller area than the surface area of ​​the plates located further from the central axis of the cyclotron.

[0014] According to one embodiment, at least some of the rotatable parts each comprise a first portion at least partially surrounding the respective axis, the first portion being located between two planes parallel to and on either side of the respective axis and made of permanent magnetic material, and another portion beyond the two planes opposite the respective axis, the other portion being made of a material with a relative magnetic permeability greater than 1.

[0015] According to one embodiment, at one position of the rotatable component, the magnitude of the vertical magnetic field is greatest within the particle acceleration chamber, and at another position of the rotatable component, the magnitude of the vertical magnetic field is least within the particle acceleration chamber.

[0016] According to one embodiment, the rotatable component is continuously rotatable.

[0017] According to one embodiment, the rotatable parts are accessible from outside the cyclotron in order to rotate them to their respective positions.

[0018] According to one embodiment, the rotatable parts are rotatable independently of each other.

[0019] According to one embodiment, the cyclotron further comprises one or more electromotive coils configured to apply a magnetic field within the chamber by energizing the coils.

[0020] According to one embodiment, the particle acceleration chamber follows a median plane between an upper part and a lower part, and the cyclotrons with rotatable parts are in two symmetrical sets with respect to the median plane.

[0021] The present invention also relates to a method for operating such a cyclotron, comprising the steps of: - rotating at least some of the rotatable components towards respective positions, where in one position of the rotatable components the magnitude of the vertical magnetic field is maximized in the particle acceleration chamber and in another position of the rotatable components the magnitude of the vertical magnetic field is minimized in the particle acceleration chamber; and / or - opening the cyclotron by separating the upper and lower parts from each other at a position of the rotatable part where the magnitude of the vertical magnetic field is minimized in the particle acceleration chamber; Includes:

[0022] In the framework of this document, the use of the indefinite article "a", "an" or the definite article "the" to introduce an element does not exclude the presence of a plurality of these elements. In this specification, the terms "first", "second", "third", etc. are used only to distinguish elements and do not imply an order of these elements.

[0023] In the framework of this document, the use of the verbs "comprise", "include", "involve" or any other similar variations and conjugations thereof cannot exclude the presence of elements other than those mentioned. If the verb "comprise" is used to define an interval by the term "comprised between" two values, these two values ​​should not be interpreted as being excluded from the interval.

[0024] All embodiments of the cyclotron according to the invention and the advantages of this embodiment apply mutatis mutandis to this method and vice versa. [Brief explanation of the drawings]

[0025] Other features and advantages of the present invention will become apparent from the following detailed description, for the understanding of which reference should be made to the accompanying drawings.

[0026] [Figure 1] 1 illustrates a cyclotron according to an embodiment. [Figure 2] The cyclotron in Figure 1 is shown. [Figure 3] 1 shows a cyclotron according to another embodiment. [Figure 4] The cyclotron is shown in Figure 3. [Figure 5] The cyclotron is shown in Figure 3. [Figure 6] 1 shows the rotatable parts of a cyclotron. [Figure 7] 1 shows the permanent magnet portion of the rotatable part of the cyclotron. [Figure 8] The coil of the cyclotron is shown.

[0027] The drawing figures are not to scale. Similar elements may be assigned by similar reference numbers in the drawings. Within the framework of this document, identical or similar elements may have the same reference numbers. The presence of reference numbers in the drawings cannot be considered limiting, especially when these numbers appear in the claims. DETAILED DESCRIPTION OF THE INVENTION

[0028] A description of preferred embodiments of the present invention will be given below with reference to figures, but the present invention is not limited by these references. In particular, the drawings or figures described below are only schematic and are in no way limiting.

[0029] 1 to 5 show different embodiments of a cyclotron 10 according to the present invention. The cyclotron 10 is a recirculating particle accelerator in which charged particles (positive ions (e.g., protons, deuterium, helions, alpha particles, etc.) or negative ions (e.g., H-, D-, etc.)) generated by an ion source are accelerated in a circular motion in a particle acceleration chamber 14 under vacuum, as shown schematically in FIG. 2 or 3. This is achieved by using a magnetic field that causes particles coming from the source to follow a circular path, or more precisely, a spiral path, in the particle acceleration chamber 14, in a median plane 13 perpendicular to the magnetic field. The cyclotron 10 has a central axis 11 perpendicular to the median plane 13. The particles are accelerated in a circular motion in the median plane 13 about the central axis 11. The central axis 11 is perpendicular to the particle acceleration chamber 14.

[0030] 1-5 show various embodiments of a cyclotron 10. The cyclotron 10 has an upper portion 101 above the median plane 13 and comprising an upper yoke. The cyclotron 10 also has a lower portion 102 below the median plane 13 and comprising a lower yoke. The cyclotron 10 also includes a return yoke 20. The return yoke closes the magnetic field. The return yoke 20 is at the periphery of the cyclotron 10. The return yoke 20 surrounds the particle acceleration chamber 14. The return yoke 20 surrounds a central region that may be defined as a cylindrical volume centered on the central axis 11. The central region may encompass the particle acceleration chamber 14. The return yoke 20 connects the upper and lower yokes. The return yoke 20 may include an upper return yoke 201 and a lower return yoke 202. The upper return yoke 201 and the lower return yoke 202 are supported by and integral with the upper and lower portions 101 and 102, respectively. Although not visible in the figures, the cyclotron 10 may include a particle injector and a central duct along the central axis 11 to enable charged particles to be injected into the particle acceleration chamber 14 at the center of the cyclotron. The central duct may be in either the upper portion 101 or the lower portion 102, for example, in the upper portion 102. Alternatively, the cyclotron 10 may include an internal particle source.

[0031] The upper portion 101 and the lower portion 102 are separated from each other by a median plane 13. The upper portion 101 and the lower portion 102 may or may not be symmetrical with respect to the median plane 13. The upper yoke of the upper portion 101 and the lower yoke of the lower portion 102 support several poles 22 (e.g., divided into sectors) arranged to have alternating zones with narrow (or reduced) gaps, called "hills," and zones with wide (or larger) gaps, called "valleys," to ensure repositioning of the particle beam within the median plane 13. According to the median plane 13 perpendicular to the central axis 11, the poles 22 of the upper and lower yokes are separated from each other by gaps that define a particle acceleration chamber 14 through which the accelerated particles circulate. The poles 22 are made of, for example, steel.

[0032] The upper part 101 and the lower part 102 are configured to be separable from each other. In other words, the cyclotron 10 is configured to be openable and closable to provide access to the interior of the cyclotron 10. This provides access to the chamber 14 and the poles 22. This facilitates adjustment of the cyclotron 10 and facilitates maintenance work on the cyclotron 10. The upper return yoke 201 and the lower return yoke 202 are also configured to be separable from each other to open the cyclotron 10.

[0033] The magnetic field is generated completely or partially by the parts 12. The parts 12 may be rotatable. In the remainder of the description, any reference to a "rotatable part 12" or "plurality of rotatable parts 12" applies to all or some of the parts 12. The present invention preferably applies to all of the rotatable parts 12.

[0034] Figures 6 and 7 show examples of the rotatable part 12, particularly its geometric shape. The rotatable part 12 is at least partially made of a permanent magnet material 16. The use of permanent magnets 16 allows for the generation of a magnetic field while optimizing power consumption, more specifically, reducing power consumption. When the cyclotron is in use, the rotatable part 12 does not consume electricity to generate a magnetic field that bends particle trajectories, which is advantageous from an environmental standpoint. According to Figure 6, the north and south poles outside the rotatable part 12 allow for the generation of a magnetic field along closed magnetic field lines between the north and south poles. When assembled in the cyclotron, the rotatable part 12 is used to generate a magnetic field within the particle acceleration chamber. In particular, the magnetic field is vertical within the particle acceleration chamber, enabling particle acceleration. The magnetic field is also closed by a return yoke 20. The permanent magnet material 16 may be SmCo (samarium cobalt), which reduces activated waste. NdFeB (neodymium-iron-boron) magnets, which are easier to activate, can also be used. The invention is not limited to these materials and other materials can be used depending on the magnetic strength required.

[0035] The rotatable components 12 extend along respective axes 18. Each of the rotatable components 12 extends along a respective axis 18. Each of said rotatable components 12 extends along a respective axis 18. In other words, one rotatable component 12 extends along one axis 18. FIG. 6 shows the axes 18 of the rotatable components 12. The rotatable components 12 extend along the axis 18. The rotatable components 12 have an elongated shape along the axis 18. The longest dimension of the component is along the axis 18. The rotatable components 12 are longer along the axis 18 compared to other dimensions. The rotatable components 12 extend essentially along one dimension, i.e., along the axis 18. The ratio between the dimension of the rotatable component along the axis 18 and the dimension transverse to the axis 18 is, for example, 2 to 3, preferably 2.5 to 2.6. Transverse to axis 18, the cross section of rotatable component 12 has the same shape along axis 18 (although it may not have the same dimensions as described below).

[0036] Further, each axis 18 is oriented such that end 121 of rotatable component 12 is closer to central axis 11 of cyclotron 10 than end 122. Each rotatable component 12 has its respective axis 18 oriented such that end 121 of rotatable component 12 is closer to central axis 11 of cyclotron 10 than end 122 of the rotatable component. In FIG. 6 , rotatable component 12 is elongated along axis 18 and extends between two ends 121, 122. Ends 121, 122 are the farthest points from the center of rotatable component 12. Ends 121, 122 are the farthest points from the center of rotatable component 12 and are located on axis 18. Axis 18 is oriented within cyclotron 10 such that end 121 is closer to axis 11 than end 122. End 121 faces central axis 11, and end 122 faces away from central axis 11, toward the periphery of the cyclotron. Axis 18 is oriented toward the central region of cyclotron 10 .

[0037] Furthermore, each of the rotatable components 12 is rotatable about its respective axis 18 between several positions. The components 12 are rotatable. The angular position of each of the rotatable components 12 is adjustable about its respective axis 18. Each of the components 12 is rotatable about its respective axis 18. In FIG. 6 , the components 12 are rotatable about their respective axes 18. Rotation of the rotatable components 12 allows the rotatable components 12 to be positioned at different angular positions about the axes 18. The rotatable components 12 are symmetrical about their respective axes 18. Whatever the plane that intersects the respective axes 18, the cross section of the rotatable components 12 in this plane has the same dimensions in all directions. In the cross section that intersects the respective axes 18, the rotatable components 12 are circular about the axes 18. Depending on the (angular) position of the rotatable components 12 within the cyclotron, the positions of the north and south poles of each rotatable component 12 change, thereby changing the strength and / or orientation of the magnetic field generated within the particle acceleration chamber 14. The magnetic field generated by the rotatable components 12 within the chamber 14 depends on the position of the rotatable components 12 about their respective axes 18. The magnetic field within the particle acceleration chamber is adjusted according to the respective positions of the rotatable components 12. This allows for a variable magnetic field and adjustment of the magnetic field within the particle acceleration chamber. Furthermore, the rotatable components 12 can be removed for replacement in the event of demagnetization of the permanent magnet material 16. The rotatable components 12 have structural rigidity to maintain rotational torque during angular adjustment.

[0038] Furthermore, each rotatable component 12 has a cross-section located near the central axis 11 of the cyclotron 10 that is smaller than other cross-sections located further from the central axis 11 of the cyclotron 10. The cross-sections of the rotatable components intersect their respective axes 18. Certain rotatable component cross-sections near the central axis 11 are smaller than other rotatable component cross-sections away from the central axis 11. In FIG. 6, the area of ​​the rotatable component cross-section near end 121 (closer to the central axis 11 than end 122) is smaller than the area of ​​the rotatable component cross-section near end 122 (closer to the periphery of the cyclotron than end 121). This allows the rotatable components 12 to be positioned within the cyclotron in an optimized manner relative to one another. The rotatable components 12 with smaller cross-sections are positioned closer to the interior of the cyclotron, and the rotatable components with larger cross-sections are positioned closer to the periphery of the cyclotron. The smaller available space in the cyclotron towards the central axis 11 is occupied by the less bulky segments of the rotatable parts 12, and the larger available space in the cyclotron towards the periphery of the cyclotron is occupied by the more bulky segments of the rotatable parts 12. This allows for optimizing the placement of the rotatable parts 12 within the cyclotron, and therefore optimizing the magnetic field in the particle acceleration chamber relative to the footprint of the cyclotron. Cyclotron 10 is compact.

[0039] Thus, by virtue of the shape, symmetry, and orientation of components 12 and axis 18, cyclotron 10 optimizes the variable magnetic field for a given cyclotron footprint. Both current consumption and footprint are optimized. Cyclotron 10 also provides a permanent magnet cyclotron that maximizes the amount of permanent magnet (and magnetic field between the poles) for a given cyclotron footprint, which magnetic field can be canceled to assist in isochronizing and / or opening the cyclotron.

[0040] In the figure, vertical holes 36 for vacuum pumps can be seen through the top 101 and / or bottom 102. This is to allow access to the particle acceleration chamber 14 for creating a vacuum. Other equipment may be inserted into the vertical holes 36. Also, radial holes 38 may be envisaged at 90° intervals around the periphery of the return yoke 20. The holes 38 are for beam extraction and equipment access.

[0041] To further optimize the variable magnetic field for a given cyclotron footprint and to facilitate its construction, each axis 18 of the rotatable elements 12 is oriented obliquely toward the median plane 13 or parallel to the median plane 13. According to FIGS. 1-5, each axis 18 is directed toward the central region of the cyclotron. In the embodiment of FIGS. 1 and 2, each axis 18 is oriented obliquely within the cyclotron 10. Each axis 18 is oriented toward the median plane 13. Each axis 18 is neither parallel nor perpendicular to the central axis 11 nor the median plane 13. Each axis 18 is oriented obliquely within the cyclotron 10, for example. The rotatable elements 12 are positioned within the cyclotron such that the distal end 121 is oriented toward the median plane 13 and the distal end 122 is oriented toward the outer periphery of the cyclotron. Each axis 18 of the rotatable elements 12 is inclined from the outer periphery of the cyclotron toward the median plane 13. For example, the angle between each axis 18 of the rotatable elements 12 and the median plane 13 is, for example, 10° to 80°, preferably 30° to 60°. In the embodiment of Figures 3 to 5, each axis 18 is oriented parallel to the median plane 13 of the cyclotron 10. Each axis 18 is horizontal. The rotatable elements 12 are positioned within the cyclotron such that the distal end 121 is not oriented toward the median plane 13 and the distal end 122 is oriented toward the outer periphery of the cyclotron. The axis 18 of each rotatable element 12 extends from one point on the outer periphery of the cyclotron to another point on the outer periphery of the cyclotron.

[0042] Even more preferably, to further improve optimization of the variable magnetic field for a particular footprint of the cyclotron and to further facilitate its construction, the axes 18 of each of the rotatable components 12 are oriented toward the central axis 11. In the embodiment of FIGS. 1 and 2, the rotatable components 12 are positioned within the cyclotron with their ends 121 oriented obliquely toward the central axis 11 and their ends 122 oriented toward the outer periphery of the cyclotron. The axes 18 of each of the rotatable components 12 are inclined from the central axis 11 toward the outer periphery of the cyclotron. The oblique orientation of each axis 18 allows for longer rotatable components 12 and therefore allows for the generation of an increased magnetic field. In the embodiment of FIGS. 3-5, the rotatable components 12 are positioned within the cyclotron with their ends 121 oriented toward the central axis and their ends 122 oriented toward the outer periphery of the cyclotron, and the axes 18 of each of the rotatable components 12 are parallel to the median plane 13. The axes 18 of each of the rotatable components are aligned along the diameter of the cyclotron 10.

[0043] The rotatable components 12 can be positioned within the return yoke 20, which allows the rotatable components 12 to be positioned around the central region of the cyclotron, particularly around the particle acceleration chamber 14. It is also easier to incorporate the rotatable components 12 into the return yoke. The return yoke 20 is provided with receptacles to accommodate the rotatable components 12. A non-magnetic partition 40 may be provided between the rotatable components 12. This prevents the magnetic field from dissipating within the material of the partition 40. Preferably, the rotatable components 12 (and therefore the permanent magnet material) are spaced away from the cyclotron median plane 13. This reduces activation from accelerated particles. Furthermore, the rotatable components may be in two sets symmetrical with respect to the median plane 13. This simplifies the manufacture of the cyclotron, aids in opening the cyclotron, and simplifies the operation of the cyclotron 10. The sets are also symmetrical with respect to the cyclotron central axis 11 to generate the maximum magnetic field.

[0044] 6 and 7, the cross-section of the rotatable element 12 decreases along the respective axis 18 towards the end 121 of the rotatable element 12 that is closer to the central axis 11. The cross-sectional area of ​​the rotatable element 12 decreases from one end 122 to the other end 121. The decrease may be continuous or discontinuous. The cross-sectional area of ​​the rotatable element 12 varies from the end 122 to the end 121. The change may be continuous or discontinuous. This optimizes the placement of the rotatable element 12 in the cyclotron.

[0045] Preferably, the diameter of the rotatable element 12 decreases over the length of the rotatable element 12. The decrease is toward the end 121. In one embodiment, the rotatable element 12 may be a series of cylinders abutting each other such that the diameter decreases stepwise toward the end 121. In a preferred embodiment, the rotatable element 12 has a frusto-conical shape, with the cross-section of the rotatable element 12 decreasing toward the end 121, which is closer to the central axis. The rotatable element 12 has a truncated conical shape. The smallest cross-section of the rotatable element 12 is closer to the interior of the cyclotron. The advantage of a frusto-conical shape is that it is easier to place within the cyclotron, makes it easier to adjust its position around the axis 18, and optimizes the use of space within the cyclotron.

[0046] Next, the manufacture of the rotatable components 12 will be described. At least some of the rotatable components have different portions. A first portion 24 at least partially surrounds each of the axes 18. The first portion 24 is parallel to the respective axes and is located between two parallel planes on either side of the respective axes 18. The first portion 24 is made of a permanent magnet material 16. Furthermore, each of the rotatable components 12 has another portion 26 beyond the two parallel planes facing the respective axes 18. Figures 6 and 7 show the manufacture of the rotatable components 12 in detail. The rotatable components 12 have interfaces 28 that are parallel to the respective axes and correspond to the planes on either side of the respective axes 18. The interfaces 28 are formed by flat surfaces on the sides, and the interfaces 28 lie along parallel planes. The interfaces 28 are parallel to the respective axes 18 on either side of the axes. The interfaces 28 are symmetrical with respect to the respective axes 18. The rotatable components 12 have two flat lateral surfaces. The interface 28 increases the magnetic flux generated by the permanent magnet material 16 while limiting the volume and cost of this material. One interface 28 is the north pole of the rotatable component 12, and the other interface 28 is the south pole. The north and south poles allow for the generation of a magnetic field along closed magnetic field lines between the north and south poles outside the rotatable component 12. Referring to the other portion 26, the portion 26 is made of a material with a relative permeability greater than 1. The material of the portion 26 completes the geometry of the rotatable component 12 in accordance with the description provided herein. In particular, the material of the portion 26 allows the component 12 to be rotatable about the axis 18. The material of the portion 26 allows for rotational symmetry in the rotatable component 12. The material of the portion 26 allows for the geometry of the rotatable component 12 to be completed at a lower cost. The material of the portion 26 is, for example, steel.

[0047] According to FIG. 7, each rotatable element 12 comprises a stack of permanent magnet plates 30 (or slabs) fixed to one another. The plates 30 located closer to the central axis 11 of the cyclotron 10 have a surface with a smaller area than the plates 30 located further from the central axis 11 of the cyclotron 10. Each plate 30 has opposite lateral sides that constitute an interface 28. The opposite lateral sides constitute a north pole and a south pole. Each plate 30 constitutes a permanent magnet of simple structure. The assembly of all the plates 30 leads to the production of a given rotatable element part 24. The stack of plates 30 constitutes the desired geometric shape of the rotatable element 12 made of permanent magnet material 16. Each plate 30 may be a cylinder whose dimension along the axis 18 is smaller than its dimension across the axis 18. That is, each plate 30 is formed in the shape of a disk. Thus, the rotatable element 12 (for example in the form of a cone) is produced from concentric disks. The disks may be small (1 cm 3 The plate 30 can be made of small cubic cells of permanent magnets, such as an aluminum frame with inserted permanent magnet cubes. The disk can be made of a larger shaped slab of permanent magnets. The use of the plate 30 makes it easier to manufacture the rotatable component 12. The rotatable component 12 is simplified for manufacturing, transportation, and / or assembly.

[0048] The manufacturing process for rotatable part 12 can be described as follows, by way of example: Permanent magnet plates 30 (or slabs) may be bolted together to form part 24. Long bolts can be used to press plates 30 together. Shorter bolts and notches can then be used to attach the plates to each other. The shape of plates 30 can be optimized to suit the manufacturing process. Steel slabs 31 (which together form part 26) can be bolted to plates 30 and adjacent steel slabs 31. It is also possible to use interconnecting notches in all plates and slabs to aid in torque transmission to rotate rotatable part 12.

[0049] Referring again to the rotatable volume of the rotatable part 12 between several positions. For example, in one position of the rotatable part 12, the magnitude of the vertical magnetic field is maximum in the particle acceleration chamber. In FIGS. 1 and 4, the rotatable part 12 is in this position. The north and south poles of the rotatable part 12 are oriented vertically so that the magnetic field is maximum in the particle acceleration chamber 14 (ON position of the part 12). In another position of the rotatable part 12, the magnitude of the vertical magnetic field is minimum in the particle acceleration chamber (OFF position of the part 12). In FIG. 5 (which also applies to the embodiment of FIG. 1), the rotatable part 12 is in this other position. The north and south poles of the rotatable part 12 are oriented horizontally. The magnitude of the vertical magnetic field is minimized in the particle acceleration chamber. In this position, the cyclotron can be opened, and the force to open the cyclotron is minimized.

[0050] The rotatable components 12 may be rotatable between discrete positions. Alternatively, the rotatable components 12 may be continuously rotatable. This allows for fine adjustment of the position of the rotatable components to adjust the magnetic field to the desired magnitude. As shown, the rotatable components 12 are accessible from the outside (or from the periphery) of the cyclotron to rotate them toward the desired position. The position of the rotatable components 12 can be adjusted manually or motorized. To adjust the angular position of the rotatable components 12, holes 32 are provided in the rotatable components 12. The holes 32 are provided throughout the plate 30. The holes 32 extend parallel to the axis 18. Rotation of the rotatable components 12 is achieved via a tool inserted into the holes 32. The rotatable components can rotate independently of each other. This also allows for fine adjustment of the position of each rotatable component 12 to adjust the (vertical) magnetic field in the chamber 14 to the desired magnitude (and reach the ON and OFF positions).

[0051] FIG. 8 illustrates a further embodiment that can be combined with the previous figures. The cyclotron 10 can further include one or more electromotive coils 34. The electromotive coils 34 are configured to apply a magnetic field within the chamber 14 by supplying power to the coils. The coils 34 can be used to adjust the magnetic field generated within the particle acceleration chamber 14. The coils 34 can be used to generate additional magnetic fields or magnetic fields that counter the magnetic field generated by the rotating component 12. The magnetic coils allow for a reduction in the size and cost of the rotatable component 12 and, therefore, the cyclotron 10. The combination of the rotatable component 12 and the coils 34, both of which generate a magnetic field, reduces the running costs of a cyclotron equipped with only coils. With such a combination, the cyclotron can be designed as a hybrid cyclotron 10. The frame of the present invention also requires smaller and less expensive power supplies. The coils 34 can be smaller and fit into smaller spaces without increasing the overall size of the cyclotron 10. This provides more space for other equipment. The coils 34 can be located in grooves within the upper and / or lower components 101 and 102. The coil 34 may be located between the end 121 of the rotatable component 12 and the pole 22. The coil 34 may be centered on the central axis 11. The coil 34 may surround the central region, more specifically the chamber 14. Furthermore, the use of a coil makes it possible to provide a rotatable component 12 with a smaller size, which reduces the permanent magnet rotation torque. Therefore, it is easier to design the rotation mechanism. The coil 34 helps the rotatable component 12 to remain magnetized.

[0052] The present invention also relates to a method for operating the cyclotron 10, which includes adjusting the magnetic field. To this end, the method includes rotating at least some of the rotatable components 12 to respective positions, where in one position of the rotatable components, the magnitude of the vertical magnetic field is maximized in the particle acceleration chamber, and in another position of the rotatable components, the magnitude of the vertical magnetic field is minimized in the particle acceleration chamber. All rotatable components 12 can be rotated and adjusted to a desired position. Other positions are also possible for adjusting the magnitude of the vertical magnetic field. Also, if a coil 34 is implemented, the position of the rotatable components 12 is adjusted as a result. This method provides flexibility in the operation of the cyclotron 10.

[0053] The method may also include the step of opening the cyclotron 10. To this end, in a position on the rotatable part 12 where the magnitude of the vertical magnetic field is minimized in the particle acceleration chamber 14, the method includes the step of opening the cyclotron by separating the upper part 101 and the lower part 102 from each other, thereby enabling an operator to carry out maintenance work in the cyclotron in a safe manner.

[0054] The magnetic field in the central region can reach up to 2 Tesla. When the magnetic field is on, magnetic flux is forced to flow through the central region and the poles 22. When the magnetic field is off, magnetic flux travels between adjacent rotatable parts 12. When on, fringe fields can be reduced by better aligning the edges of the rotatable parts 12 with the yoke.

[0055] The proposed solution for the cyclotron, which has two rows of cone-shaped components with permanent magnets in the return yoke, allows the magnetic field to be varied and / or turned off for adjustments and / or interventions. These permanent magnets are built into a cone shape that can be rotated. This can also be supplemented with lower current coils to keep power consumption low. The variable magnetic field generated within the cyclotron 10 allows the cyclotron to turn off and open the magnetic field. The cyclotron 10 is a compact cyclotron optimized to provide a high magnetic field and offers flexibility for easy cyclotron maintenance. The magnetic field of the cyclotron 10 can be adjusted to maintain isochronism (especially using a magnetic field measurement device) as the permanent magnets demagnetize. When turned on, the magnetic field can be returned to the same value (less than 2 Gauss difference) after the magnetic field is turned off. The cyclotron 10 is radiation-hard.

[0056] Note that some of the components 12 may be rotatable and other components 12 may not be rotatable. For example, half of the components 12 may be rotatable and half of the components 12 may be non-rotatable. The rotatable and non-rotatable components may have the same design (non-rotatable and rotatable components that release when rotated to the off position, which is 180 degrees from the on position).

[0057] Although the present invention has been described in relation to specific embodiments, these are purely illustrative and should not be considered limiting. Generally speaking, it will be clear to those skilled in the art that the present invention is not limited to the examples illustrated and / or described above.

Claims

1. In the cyclotron (10), a particle acceleration chamber (14), a rotatable part (12) for generating a magnetic field within said particle acceleration chamber; an upper part (101) above the particle acceleration chamber (14) and a lower part (102) below the particle acceleration chamber (14), the upper part (101) and the lower part (102) being configured to be separable from each other; Equipped with At least a portion of the rotatable component (12) each formed at least in part from permanent magnetic material (16); each extending along a respective axis (18), said respective axes being oriented such that an end (121) of said rotatable component (12) is closer to the central axis (11) of said cyclotron than another end; each rotatable about its respective axis (18) between several positions, the magnetic field generated by said rotatable parts (12) within said chamber (14) being dependent on the position of said rotatable parts (12) about their respective axis (18); each having a cross section located near the central axis (11) of the cyclotron that is smaller than other cross sections located further from the central axis (11) of the cyclotron, the cross sections of the rotatable parts (12) transverse to their respective axes (18); Cyclotron (10).

2. 2. The cyclotron (10) of claim 1, wherein the cross-sections of the rotatable components (12) decrease along the respective axes (18) toward the ends (121) of the rotatable components (12) closer to the central axis (11).

3. 2. The cyclotron (10) of claim 1, wherein the rotatable component (12) has a frustoconical shape, the cross section of the rotatable component decreasing towards the end (121) of the rotatable component closer to the central axis (11).

4. The cyclotron (10) of any one of claims 1 to 3, further comprising a return yoke (20) surrounding the particle acceleration chamber (14), the rotatable part (12) being within the return yoke.

5. 4. The cyclotron (10) of claim 1, wherein the particle acceleration chamber (14) follows a median plane (13), and the axes (18) of the respective rotatable parts (12) are oriented obliquely towards the median plane (13) or parallel to the median plane (13).

6. The cyclotron (10) of any one of claims 1 to 3, wherein the axes of the respective rotatable parts (12) point towards the central axis (11).

7. each of said rotatable parts (12) comprising a stack of permanent magnet plates (30) fixed to one another; 4. The cyclotron (10) of claim 1, wherein a plate (30) located near the central axis (11) of the cyclotron has a surface with an area smaller than a surface area of ​​a plate (30) located farther from the central axis (11) of the cyclotron.

8. At least some of the rotatable components (12) each include: a first part (24) at least partially surrounding said respective axis (18), being located between two planes parallel to and on either side of said respective axis (18), said first part (24) consisting of permanent magnetic material (16); - other parts (26) beyond the two planes opposite the respective axes (18), made of a material with a relative permeability greater than 1; The cyclotron (10) of any one of claims 1 to 3, comprising:

9. 4. The cyclotron (10) of claim 1, wherein at one position of the rotatable part (12), the magnitude of the vertical magnetic field is maximum in the particle acceleration chamber (14), and at another position of the rotatable part (12), the magnitude of the vertical magnetic field is minimum in the particle acceleration chamber (14).

10. The cyclotron (10) of any one of claims 1 to 3, wherein the rotatable part (12) is continuously rotatable.

11. The cyclotron (10) of any one of claims 1 to 3, wherein the rotatable parts (12) are accessible from outside the cyclotron for rotating them to their respective positions.

12. The cyclotron (10) of any one of claims 1 to 3, wherein the rotatable parts (12) are rotatable independently of one another.

13. 4. The cyclotron (10) of claim 1, further comprising one or more electric coils (34), the electric coils (34) configured to apply a magnetic field within the chamber (14) by powering the coils (34).

14. 4. The cyclotron (10) according to claim 1, wherein the particle acceleration chamber (14) follows a median plane (13) between the upper part (101) and the lower part (102), and the cyclotrons with the rotatable parts (12) form two symmetrical sets with respect to the median plane (13).

15. A method for operating a cyclotron (10) according to any one of claims 1 to 3, comprising the steps of: - rotating at least some of the rotatable parts (12) towards respective positions, in which in one position of the rotatable parts (12) the magnitude of the vertical magnetic field is maximized in the particle acceleration chamber (14) and in another position of the rotatable parts (12) the magnitude of the vertical magnetic field is minimized in the particle acceleration chamber (14); and / or - opening the cyclotron by separating the upper part (101) and the lower part (102) from each other at the position of the rotatable part (12) where the magnitude of the vertical magnetic field is minimized in the particle acceleration chamber (14); A method comprising:

Images