High-brightness X-ray source

Abstract

A method for generating an X-ray beam, the method comprising: (a) directing an X-ray generating fluid toward a cryogenic X-ray emitting target; (b) freezing the X-ray generating fluid with the cryogenic X-ray emitting target to provide a frozen X-ray generating material; and (c) irradiating the frozen X-ray generating material with an electron beam to generate the X-ray beam.

Description

[Technical Field]

[0001] This application claims priority from U.S. Provisional Patent Application No. 63 / 365,414, filed May 26, 2022, which is incorporated by reference in its entirety. [Background technology]

[0002] There is an increasing need for high brightness x-ray sources for metrology and inspection. Summary of the Invention

[0003] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. However, the invention, both as to organization and method of operation, together with its objects, features, and advantages, may best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0004] [Figure 1] 1 shows an example of an X-ray source that includes a photocathode. [Figure 2] 1 shows an example of an X-ray source that includes a photocathode. [Figure 3] 1 shows an example of an X-ray source that includes a photocathode. [Figure 4] 1 shows an example of an X-ray source that includes a photocathode. [Figure 5] An example of the method is shown below. [Figure 6] An example of an electron beam-X-ray conversion optical system is shown. [Figure 7] An example of an electron beam-X-ray conversion optical system is shown. [Figure 8] An example of the method is shown below. DETAILED DESCRIPTION OF THE INVENTION

[0005] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

[0006] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. However, the invention, both as to organization and method of operation, together with its objects, features, and advantages, may best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

[0007] It will be understood that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Furthermore, where appropriate, reference numerals may be repeated among the figures to indicate corresponding or similar elements.

[0008] The illustrated embodiments of the present invention can be implemented, for the most part, using electron beam components and circuits known to those skilled in the art, and will not be described in more detail than is deemed necessary as illustrated for an understanding and appreciation of the basic concepts of the present invention and in order not to obscure or detract from the teachings of the present invention.

[0009] Any reference in this specification to a method should be applied mutatis mutandis to a system capable of carrying out that method.

[0010] References in this specification to a system should apply mutatis mutandis to methods that can be performed by said system.

[0011] For metrology and inspection, high brightness (e.g. photon flux >1×10) is possible 10 An X-ray source of 1000 Hz (ph / s) is provided. a. Higher throughput b. Higher quality x-ray beam c. Alternative Architecture d. Other technologies (dimensional measurement, material measurement, ptychography, inspection) e. Adjustable from low to high energy (100 eV to several tens of KeV)

[0012] The proposed X-ray source is more cost-effective than solutions based on discharge or pinch plasma (which also have low brightness), solid tape laser produced plasma (LPP), gas jet LPP, liquid LPP, and cryogenic LPP, all of which are too expensive for metrology applications.

[0013] Commercially available electron beam sources, such as thermionic or field emission sources, can also be used, with some limitations. Thermionic sources are usually made from tungsten or lanthanum hexaboride (LaB6). In thermionic emission, electrons boil off from a material surface when the electron thermal energy is high enough to overcome a surface potential barrier. Thermionic emitters are widely used, but they typically require high temperatures (e.g., >1300 K) to operate and suffer from drawbacks such as inefficient power consumption, wide energy spread, short lifetime, low current density, and limited brightness.

[0014] More efficient and brighter electron sources are available, such as Schottky emitters and cold electron field emitter sources, but these are susceptible to contamination and require very high vacuum levels, although these technologies can address some of these concerns.

[0015] X-ray sources containing photocathodes have been proposed, and this technology can address most of these concerns, allowing high brightness X-ray sources to be created.

[0016] Photocathodes are important in accelerator physics, where they are used in photoinjectors to generate high-brightness electron beams. Electron beams generated using photocathodes are often used in free-electron lasers and ultrafast electron diffraction. Photocathodes are also commonly used as negatively charged electrodes in light-detecting devices such as photomultipliers and phototubes.

[0017] In its simplest form, an x-ray source includes a photocathode and optical elements configured to receive an incident radiation beam (eg, a light beam) and shape, collimate, and focus it at the surface of the photocathode.

[0018] The photocathode surface produces a high-intensity electron beam with a very small energy spread. The electron beam is then focused onto a sample (target) to produce a high-intensity X-ray beam. The target material can be selected to optimize the X-ray energy. By carefully selecting the material, X-rays with energies from 100 eV to tens of keV are possible. This target material is sometimes called the "X-ray material."

[0019] The optics of an X-ray source can focus a light beam to diffraction-limited dimensions governed by the wavelength and the numerical aperture (NA) of the optical system. For example, for a laser system with wavelength λ, a lens of focal length f can be used to focus a Gaussian beam to a beam waist w o The final waist f ·w f=λf / πw o It can be made into.

[0020] Therefore, the spot size can be made very small: in the case of ultraviolet (UV) lasers, this spot can be made less than 1 micron in diameter.

[0021] The electron beam produced by the X-ray source can be shaped into any desired shape by using optical elements such as filters, masks or electron optical elements using mask sand filters.

[0022] The photocathode emits electrons with properties that depend on the shape of the driving laser: for example, it can be Gaussian-shaped or a flat-top beam, or it can be ring-shaped, annular, or any desired shape.

[0023] Photocathodes may be preferred over other forms of cathodes because they allow for better control over the quality of the electron beam output from the photocathode.

[0024] When a light beam strikes a photocathode, it releases electrons by applying the photoelectric effect. The photoelectric effect conserves the energy and momentum of the incident light beam. Therefore, the properties of the light beam are also conserved in the photoelectron beam. For example, when a light beam strikes a photocathode, many of the parameters of a laser beam, such as energy spread and stability, are preserved.

[0025] The photocathode of the X-ray source is illuminated by any type of light produced by a variety of sources, such as a lamp, plasma, laser-produced plasma, discharge plasma, diode, or laser.

[0026] The light beam may be continuous (eg, CW) or pulsed.

[0027] When using a photocathode, the X-ray source can maintain an energy spread or dispersion (of the photon-electron beam) as low as 0.1 eV compared to conventional thermal emission guns (>1 eV) or field emission systems (>0.3 eV).

[0028] Low energy spread of the electron beam can be an important parameter to enable the production of high quality electron beams and small spot sizes with very small energy tails.

[0029] Very small levels of energy dispersion cannot be produced with conventional electron beams. The smaller the energy dispersion, the better the beam quality, and the better the quality of a small electron spot size. A small energy dispersion also makes it easier to initially obtain a nearly collimated electron beam. A spot size of 200 μm diameter or less is desirable.

[0030] 1 illustrates a transmission type X-ray source, which includes a radiation source, such as a photon beam source 20, such as (but not limited to) a laser, configured to direct radiation (such as a light beam 11) toward a transparent substrate 30, which mechanically supports a photocathode 40. The light beam 11 is incident on one side of the photocathode 40, causing electrons to be emitted from the other side of the photocathode, forming an electron beam 12. The electron beam 12 is attracted to a control grid 50 (biased relative to the photocathode 40 by a bias circuit 70, which determines the energy of the electrons emitted from the control grid) and strikes an X-ray emitting target 60, generating an X-ray beam 13.

[0031] 2 illustrates a reflective x-ray source, which includes a radiation source, such as a photon beam source 20, such as (but not limited to) a laser, configured to direct radiation (such as a light beam 11) toward a photocathode 40. The photocathode 40 is supported by a substrate 31. The light beam 11 strikes one side of the photocathode 40, causing electrons to be emitted from the same side, forming an electron beam 12. The electron beam 12 is attracted to a control grid 50 (biased relative to the photocathode 40 by a bias circuit 70, the bias determining the energy of the electrons emitted from the control grid) and strikes an x-ray emitting target 60, producing an x-ray beam 13.

[0032] By using electron beam optics (located between the photocathode and the x-ray material), the high quality electron beam 12 can also be shaped and focused to a very small spot size.

[0033] The electron optical system may include at least some components of an electron beam column, such as one or more apertures, and / or one or more deflectors, and / or one or more scan coils, and / or one or more electromagnetic lenses, and / or one or more magnetic lenses, and / or one or more detectors.

[0034] The configuration of the electron optics can vary depending on the specific application of the system. The electron energy ranges from 100 eV to tens of keV. The electron spot size on the x-ray material can be smaller than 50 μm.

[0035] The electron beam can then be focused onto an X-ray emitting target made of solid X-ray material, which may be made of (or contain) a liquid or gas, and produces X-rays with a very well-defined X-ray spot.

[0036] Although Figures 1 and 2 show a transmission mode X-ray emitting target, the X-ray emitting target may also be a reflection mode X-ray emitting target.

[0037] FIG. 3 shows an X-ray source with a reflective X-ray emitting target.

[0038] FIG. 4 shows an example of an X-ray source, which has an electron optical system 80 between a control grid 50 and an X-ray emitting target.

[0039] The substrate (which supports the photocathode) can be made of a material selected depending on the wavelength of the radiation beam. For example, for UV (ultraviolet) wavelengths up to 248 nm, fused silica or sapphire can be used as the substrate material. For wavelengths below 190 nm, high-grade fused silica can be used. For wavelengths below 190 nm, MgF2 or CaF2 can be used. The photocathode material can be selected for optimal quantum efficiency (QE), energy spread, and desired lifetime at a given wavelength.

[0040] The photocathode can be selected to produce high brightness for the wavelength of the radiation beam, for example, the material of the photocathode can be selected depending on the wavelength or whether it is in transmissive or reflective mode, and can have different coatings or different substrates.

[0041] The photocathodes of choice include semiconductors, semiconductor alloys, metals, metal alloys, and hybrid systems.

[0042] For example, semiconductor PCs (photocathodes) that can be used include Cs2Te, CsK2Sb, GaAs, Cs2Te, CsK2Sb, K2CsSb, Cs:GaAs, GaAs, AlGaN, one or more alloys formed from AlGaN and GaN, InGaN, InGaP, InGaP, GaP, GaN, GaP, CsI, CsBr, or alkali halide photocathodes.

[0043] FIG. 5 illustrates an example method 200 for generating an x-ray beam.

[0044] The method 200 begins at step 210 by irradiating the photocathode with a light beam.

[0045] Step 210 is followed by step 220, in which an electron beam is generated by the photocathode and due to the irradiation.

[0046] Step 220 can be performed with the photocathode operating in a transmission mode.

[0047] Step 220 can be performed with the photocathode operating in a reflective mode.

[0048] Step 220 is followed by step 230, in which the electron beam is converted into an x-ray beam.

[0049] The spot size of the light beam may be on a microscopic scale.

[0050] Electron beams can exhibit an energy spread of less than 0.3 electron volts.

[0051] The photocathode can include fused silica or sapphire, which can be used as the substrate material.

[0052] The photocathode can be made of MgF2, CaF2, BaF2 or LiF2.

[0053] The photocathode can be made from at least one material out of Cs2Te, CsK2Sb, GaAs, Cs2Te, CsK2Sb, K2CsSb, Cs:GaAs, GaAs, AlGaN, one or more alloys formed with AlGaN or GaN, InGaN, InGaP, InGaP, GaP, GaN, GaP, CsI, CsBr, or alkali halide.

[0054] The light beam, electron beam, and X-ray beam may be a continuous beam or a pulsed beam.

[0055] Hybrid X-ray sources are also available. For example, thermionic cathode materials use a thermally assisted photoemission process. For example, a LaB6 or CeB6 cathode is heated and uses a light source to assist the electron emission process. They have already been used successfully as photocathodes.

[0056] The material for generating X-rays may be any of the following: a. Gas jet, pressurized gas jet. b. Cryogenic gas (gas), liquid or solid. c. A solid bulk material used in reflection mode. d. Thin films used in transmission or reflection mode. e. Tape. f.Liquid metal.

[0057] X-ray sources can use the above materials in a variety of configurations. For example, gas jets are convenient target materials because gases produce less debris than liquids or solids.

[0058] Gas jets can also easily deliver lightweight Z materials, such as alcohols or light organics such as ethanol, O2, CO2, or H2O, H2O2. Low Z materials deployed in gas jets can be used to generate wavelengths from photons with energies ranging from tens of eV to hundreds of eV, depending on the pressure and composition of the gas. X-ray collection can be positioned at various angles or shapes relative to the gas jet, as illustrated in Figure 5.

[0059] FIG. 6 shows an example of an electron beam-X-ray conversion optical system that can follow any one of the control grids 50 shown in FIGS.

[0060] The electron beam to X-ray conversion optics is capable of converting the electron beam 152 (generated by the electron beam source 502 and focused by the focusing element 162) into an X-ray beam 156, which is assisted by a gas jet 154 (generated by the X-ray generating fluid source 503) to provide the required material from said conversion.

[0061] The X-ray beam can propagate at any angle or other geometric relationship to the propagation direction of the gas jet. An X-ray generation assisting unit 504 (such as a cryogenic X-ray target) assists in the generation of X-rays, improving the conversion of the electron beam to the X-ray beam, for example, when using a gas jet or liquid jet.

[0062] FIG. 7 shows an X-ray generating auxiliary unit such as a cryogenic X-ray emitting target 170 (which may be a cryogenic solid anode) that improves the conversion by condensing (freezing) the gas or liquid (from the X-ray generating fluid source 503) into a denser substance (e.g., a solid) with more molecules per unit area, thereby allowing the electron beam 152 (produced by the electron beam source 502) to interact with more molecules during electron beam to X-ray beam conversion, improving the conversion and resulting in a brighter X-ray beam 156.

[0063] Figure 7 also shows (from left to right) an example of a drop 158-1 of fluid 158 (also called X-ray generating fluid) approaching a cryogenic X-ray emitting target 170, contacting the cryogenic X-ray emitting target 170, freezing, and forming a solid element 159-1 (also called frozen X-ray generating material) that interacts with electron beam 152 to form X-ray beam 156.

[0064] Such interactions may slightly damage the cryogenic X-ray emitting target, and it may be beneficial to move the cryogenic X-ray emitting target (by a mechanical unit 510 including a motor) so that different areas of the cryogenic X-ray emitting target are eroded over time. The movement may be rotational and / or linear, etc.

[0065] For measurement and inspection purposes, an electron beam-X-ray conversion optical system as shown in FIG. 7 can be used to generate an X-ray beam in the energy range of 10 eV to several tens of keV.

[0066] The X-ray sources exemplified above can provide high-quality, potentially semi-coherent, high-brightness electron beams, which can be used to provide high-quality, semi-coherent, high-brightness X-ray beams. The X-ray beams are tunable in the energy range from 10 eV to 10 keV. These properties are important for enabling rapid acquisition of XPS and XRF data, but also enable other advanced techniques and methods of XRS, such as ptychography.

[0067] These high-brilliance X-ray sources enable a wide range of techniques, including dimensional metrology, material property measurements, semiconductor inspection, battery testing, and X-ray diffraction imaging for biological and biomedical applications.

[0068] FIG. 8 illustrates an example method 300 for generating an x-ray beam.

[0069] The method 300 may include a preliminary step 305 of generating an electron beam. The electron beam may be generated by illuminating a photocathode with a light beam. The preliminary step 305 may include receiving the electron beam.

[0070] The electron beam may be a continuous electron beam or a pulsed electron beam.

[0071] The method 300 may include a step 310 of directing an x-ray generating fluid toward a cryogenic x-ray emitting target.

[0072] The X-ray generating fluid may be an X-ray generating liquid or an X-ray generating gas.

[0073] Step 310 is followed by step 320, in which the x-ray generating fluid is frozen by a cryogenic x-ray emitting target to provide a frozen x-ray generating material.

[0074] The method 300 may also include a step 330 of irradiating the frozen x-ray generating material with an electron beam to generate an x-ray beam.

[0075] Step 330 can be performed while the frozen x-ray generating material is disposed on a cryogenic x-ray emitting target.

[0076] Steps 310, 320, and 330 can be repeated multiple times.

[0077] The method 300 may include a step 340 of introducing movement between the cryogenic x-ray emitting target and the point of interaction of the electron beam and the frozen x-ray generating material.

[0078] The movement may be a rotational movement of the cryogenic X-ray emitting target or some other movement.

[0079] The X-ray beam may include one or more Kα rays and radiation of a range of energies from 100 eV to tens of KeV.

[0080] A method for generating an x-ray beam can be provided, the method can include directing an x-ray generating fluid towards a cryogenic x-ray emitting target, freezing the x-ray generating fluid with the cryogenic x-ray emitting target to provide a frozen x-ray generating material, and irradiating the frozen x-ray generating material with an electron beam to generate the x-ray beam.

[0081] The irradiation can be performed while the frozen x-ray generating material is disposed on the cryogenic x-ray emitting target.

[0082] The method may include introducing motion between the cryogenic x-ray emitting target and a point of interaction between the electron beam and the frozen x-ray generating material.

[0083] The introducing of the movement may include rotating the cryogenic X-ray emitting target.

[0084] The x-ray generating fluid may be an x-ray generating liquid.

[0085] The x-ray generating fluid may be an x-ray generating gas.

[0086] The method may include generating the electron beam with a high brightness thermal field emitter.

[0087] The high brightness thermal field emitter may be a Schottky electron beam source.

[0088] The method may include generating the electron beam with a high brightness cold electron field emitter source.

[0089] The method may include generating the electron beam by irradiating the photocathode with a beam selected from a light beam and a laser beam.

[0090] The electron beam may be a continuous electron beam.

[0091] The electron beam may be a pulsed electron beam.

[0092] The X-ray beam may include one or more Kα rays and continuum energy radiation between 100 eV and tens of KeV.

[0093] An X-ray beam source is provided, which may include an X-ray generating fluid source configured to direct an X-ray generating fluid towards a cryogenic X-ray emitting target, a cryogenic X-ray emitting target configured to freeze the X-ray generating fluid to provide a frozen X-ray generating material, and an electron beam source configured to irradiate the frozen X-ray generating material with an electron beam to generate an X-ray beam.

[0094] The electron beam source may be configured to irradiate the frozen x-ray producing material while the frozen x-ray producing material is disposed on the cryogenic x-ray emitting target.

[0095] The X-ray beam source may include a mechanical unit configured to introduce movement between the cryogenic X-ray emitting target and a point of interaction of the electron beam and the frozen X-ray generating material.

[0096] The mechanical unit may be configured to rotate the cryogenic X-ray emitting target.

[0097] The x-ray generating fluid may be an x-ray generating liquid.

[0098] The x-ray generating fluid may be an x-ray generating gas.

[0099] The electron beam source may include a high brightness thermal field emitter.

[0100] The high brightness thermal field emitter may be a Schottky electron beam source.

[0101] The electron beam source may include a high brightness cold field emitter source.

[0102] The electron beam source may include a photocathode and a beam source configured to illuminate the photocathode with a beam selected from a light beam and a laser beam.

[0103] The electron beam may be a continuous electron beam.

[0104] The electron beam may be a pulsed electron beam.

[0105] The X-ray beam may include one or more Kα rays and continuous energy radiation ranging from 100 eV to tens of KeV.

[0106] A method for generating an X-ray beam is provided, which may include irradiating a photocathode with a photon beam selected from a light beam and a laser beam, generating an electron beam by the photocathode and due to the irradiation, and converting the electron beam into an X-ray beam.

[0107] The photon beam has a diameter not exceeding 200 microns.

[0108] The photocathode may be a transmissive photocathode.

[0109] The photocathode may be a reflective photocathode.

[0110] The electron beam exhibits an energy spread of less than 0.5 electron volts.

[0111] The photocathode is made of fused silica or sapphire, which may also be used as the substrate material.

[0112] The photocathode substrate can be made of MgF2, CaF2, BaF2 or LiF2.

[0113] The photocathode may be formed from at least one of Cs2Te, CsK2Sb, GaAs, Cs2Te, CsK2Sb, K2CsSb, Cs:GaAs, GaAs, AlGaN, one or more alloys formed from AlGaN or GaN, InGaN, InGaP, InGaP, GaP, GaN, GaP, CsI, CsBr, or an alkali halide.

[0114] The photon beam, electron beam, and X-ray beam may be a continuous beam.

[0115] The photon beam, electron beam, and X-ray beam may be a pulsed beam.

[0116] An X-ray source is provided, which includes a photon beam source configured to irradiate a photocathode with a photon beam selected from a light beam and a laser beam, and the photocathode is configured to generate an electron beam due to the irradiation, and may include an electron beam-to-X-ray beam converter configured to convert the electron beam into an X-ray beam.

[0117] The diameter of said photon beam does not exceed 200 microns.

[0118] The photocathode may be a transmissive photocathode.

[0119] The photocathode may be a reflective photocathode.

[0120] The electron beam exhibits an energy spread of less than 0.5 electron volts.

[0121] The photocathode may be made of fused silica or sapphire.

[0122] The photodiode substrate may be made of MgF2, CaF2, BaF2 or LiF2.

[0123] The photocathode may be formed from at least one of Cs2Te, CsK2Sb, GaAs, Cs2Te, CsK2Sb, K2CsSb, Cs:GaAs, GaAs, AlGaN, one or more alloys formed from AlGaN or GaN, InGaN, InGaP, InGaP, GaP, GaN, GaP, CsI, CsBr, or an alkali halide.

[0124] The photon beam, electron beam, and X-ray beam may be a continuous beam.

[0125] The photon beam, electron beam, and X-ray beam may be a pulsed beam.

[0126] A method of generating an X-ray beam is provided and may include irradiating an X-ray target with a high brightness thermal field emitter electron beam source and converting the electron beam into an X-ray beam by the X-ray target.

[0127] A method of generating an X-ray beam is provided and may include irradiating an X-ray target with a high brightness Cold Field Emitter electron beam source and converting the electron beam by the X-ray target into an X-ray beam.

[0128] A non-transitory computer readable medium is provided that stores instructions that, once executed by a controller (e.g., a controller having an integrated circuit), cause the controller to control any of the methods illustrated herein.

[0129] Although the invention has been described herein with reference to specific embodiments thereof, it will be apparent that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims.

[0130] Furthermore, terms such as "front," "rear," "top," "bottom," "over," "under," and the like, if any, used in this specification and claims are used for descriptive purposes and are not necessarily used to describe permanent relative positions. It is understood that terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are operable, for example, in orientations other than those illustrated or otherwise described herein.

[0131] Any arrangement of components to achieve the same functionality is substantially "associated" such that the desired functionality is achieved. Thus, for purposes of this specification, any two components that combine to achieve a particular functionality can be considered to be "associated" with each other such that the desired functionality is achieved, regardless of architecture or intervening components. Likewise, any two components so associated can also be considered to be "operably connected" or "operably coupled" with each other to achieve the desired functionality.

[0132] Furthermore, those skilled in the art will recognize that the boundaries between operations described above are merely illustrative. Multiple operations may be combined into a single operation, a single operation may be distributed among additional operations, or operations may perform with at least partial overlap in time. Furthermore, alternative embodiments may include multiple instances of an operation, and the order of operations may be changed in various other embodiments.

[0133] However, other modifications, variations, and alternatives are possible. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

[0134] References to "comprising" may apply mutatis mutandis to the terms "consisting" and "consisting essentially of."

[0135] In the claims, reference signs placed between parentheses shall not be construed as limiting the scope of the claim. The word "comprising" does not exclude the presence of other elements or steps than those recited in the claim. Furthermore, as used in this specification, the singular terms "a" or "an" are defined as one or more. Also, the use of introductory phrases such as "at least one" and "one or more" in a claim shall not be construed as implying that the introduction of another claim element with an indefinite article ("a" or "an") limits a particular claim containing such introduced claim element to an invention containing only one such element, even if the same claim also contains the introductory phrases "one or more" or "at least one" and an indefinite article such as "a" or "an." The same applies to the use of definite articles. Unless otherwise specified, terms such as "first" and "second" are used to arbitrarily distinguish between elements described by such terms. Thus, these terms are not necessarily intended to indicate a temporal or other priority of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

[0136] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

1. directing the x-ray generating fluid towards a cryogenic x-ray emitting target; freezing the x-ray generating fluid with the cryogenic x-ray emitting target to provide a frozen x-ray generating material; irradiating the frozen X-ray generating material with an electron beam to generate an X-ray beam; A method for generating an x-ray beam.

2. the irradiation is performed while the frozen x-ray generating material is disposed on the cryogenic x-ray emitting target; The method of claim 1.

3. introducing motion between the cryogenic x-ray emitting target and a point of interaction between the electron beam and the frozen x-ray generating material; The method of claim 1.

4. said introducing movement includes rotating said cryogenic X-ray emitting target; The method of claim 3.

5. The X-ray generating fluid is an X-ray generating liquid. The method of claim 1.

6. the X-ray generating fluid is an X-ray generating gas; The method of claim 1.

7. generating the electron beam by a high brightness thermal field emitter; The method of claim 1.

8. The high brightness thermal field emitter is a Schottky electron beam source. The method of claim 7.

9. generating said electron beam by a high brightness cold field emitter source; The method of claim 1.

10. generating the electron beam by irradiating a photocathode with a beam selected from a light beam and a laser beam; The method of claim 1.

11. the electron beam is a continuous electron beam; The method of claim 1.

12. The electron beam is a pulsed electron beam. The method of claim 1.

13. The electron beam includes one or more Kα rays and continuous energy radiation ranging from 100 eV to several tens of KeV. The method of claim 1.

14. an x-ray generating fluid source configured to direct the x-ray generating fluid toward the cryogenic x-ray emitting target; a cryogenic x-ray emitting target configured to freeze the x-ray generating fluid to provide a frozen x-ray generating material; an electron beam source configured to irradiate the frozen X-ray generating material with an electron beam to generate an X-ray beam; X-ray beam source.

15. the electron beam source is configured to irradiate the frozen x-ray generating material while the frozen x-ray generating material is disposed on the cryogenic x-ray emitting target; 15. An X-ray beam source according to claim 14.

16. a mechanical unit configured to introduce movement between the cryogenic x-ray emitting target and a point of interaction of the electron beam and the frozen x-ray generating material; 15. An X-ray beam source according to claim 14.

17. the mechanical unit is configured to rotate the cryogenic X-ray emitting target; 17. An X-ray beam source according to claim 16.

18. 15. The x-ray beam source of claim 14, wherein the x-ray generating fluid is an x-ray generating liquid.

19. 15. The x-ray beam source of claim 14, wherein the x-ray generating fluid is an x-ray generating gas.

20. 15. The x-ray beam source of claim 14, wherein the electron beam source comprises a high brightness thermal field emitter.

21. 21. The x-ray beam source of claim 20, wherein the high brightness thermal field emitter is a Schottky electron beam source.

22. 15. The x-ray beam source of claim 14, wherein the electron beam source comprises a high brightness cold field emitter source.

23. 15. The x-ray beam source of claim 14, wherein the electron beam source comprises a photocathode and a beam source configured to illuminate the photocathode with a beam selected from the group consisting of a light beam and a laser beam.

24. 15. The X-ray beam source of claim 14, wherein the electron beam is a continuous electron beam.

25. 15. The X-ray beam source of claim 14, wherein the electron beam is a pulsed electron beam.

26. 15. The X-ray beam source of claim 14, wherein the X-ray beam comprises one or more Kα rays and continuous energy radiation from 100 eV to several tens of KeV.

27. irradiating the photocathode with a photon beam selected from a light beam and a laser beam; generating an electron beam by the photocathode and due to the irradiation; converting the electron beam into an X-ray beam; A method for producing x-rays.

28. 28. The method of claim 27, wherein the photon beam has a diameter not exceeding 200 microns.

29. 28. The method of claim 27, wherein the photocathode is a transmissive photocathode.

30. 28. The method of claim 27, wherein the photocathode is a reflective photocathode.

31. 28. The method of claim 27, wherein the electron beam exhibits an energy spread of 0.5 electron volts or less.

32. 28. The method of claim 27, wherein the photocathode is made of fused silica or sapphire used as a substrate material.

33. The photocathode substrate is MgF ２ , CaF ２ , BaF ２ or LiF ２ The method of claim 27,

34. 28. The method of claim 27, wherein the photocathode is formed from at least one of CsTe, CsKSb, GaAs, CsTe, CsKSb, KCsSb, Cs:GaAs, GaAs, AlGaN, one or more alloys formed from AlGaN or GaN, InGaN, InGaP, InGaP, GaP, GaN, GaP, CsI, CsBr, or an alkali halide.

35. 28. The method of claim 27, wherein the photon beam, electron beam, and x-ray beam are continuous beams.

36. 28. The method of claim 27, wherein the photon beam, electron beam, and X-ray beam are pulsed beams.

37. a photon beam source configured to irradiate a photon beam selected from a light beam and a laser beam onto a photocathode, the photocathode configured to generate an electron beam as a result of the irradiation; an electron beam-to-X-ray beam converter configured to convert the electron beam into an X-ray beam; X-ray source.

38. 28. The x-ray source of claim 27, wherein the photon beam has a diameter not exceeding 200 microns.

39. 28. The x-ray source of claim 27, wherein the photocathode is a transmission photocathode.

40. 28. The x-ray source of claim 27, wherein the photocathode is a reflective photocathode.

41. 28. The x-ray source of claim 27, wherein the electron beam exhibits an energy spread of 0.5 electron volts or less.

42. 28. The x-ray source of claim 27, wherein the photocathode is made of fused silica or sapphire.

43. The photodiode substrate is MgF ２ , CaF ２ , BaF ２ or LiF ２ 28. The X-ray source of claim 27,

44. 28. The x-ray source of claim 27, wherein the photocathode is formed from at least one of CsTe, CsKSb, GaAs, CsTe, CsKSb, KCsSb, Cs:GaAs, GaAs, AlGaN, one or more alloys formed from AlGaN or GaN, InGaN, InGaP, InGaP, GaP, GaN, GaP, CsI, CsBr, or an alkali halide.

45. 28. The x-ray source of claim 27, wherein the photon beam, electron beam, and x-ray beam are continuous beams.

46. 28. The x-ray source of claim 27, wherein the photon beam, electron beam, and x-ray beam are pulsed beams.

47. irradiating an X-ray target with a high brightness thermal field emitter electron beam source; converting the electron beam into an X-ray beam by the X-ray target; A method for generating an x-ray beam.

48. irradiating an X-ray target with a high brightness cold field emitter electron beam source; converting the electron beam into an X-ray beam by the X-ray target; A method for generating an x-ray beam.

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