Apparatus and method for producing neutrons
The device and procedure for neutron production leverage a compact ultra-short pulse laser source and laser Wakefield Acceleration to efficiently generate neutrons, addressing the high-cost and infrastructure-intensive challenges of existing methods.
Patent Information
- Application Number
- PCT/EP2024/076740
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-09-27
- Filing Date
- 2024-09-24
- Publication Date
- 2025-04-03
AI Technical Summary
Existing neutron production methods, particularly those using particle accelerators, require large and costly infrastructure, and the laser-based acceleration methods are demanding in terms of high-performance laser sources.
A device and procedure that utilize a compact and cost-effective ultra-short pulse laser source, combined with non-linear pulse compression and laser Wakefield Acceleration, to generate a quasi-monoenergetic electron beam that interacts with a target to produce neutrons.
The solution enables efficient, robust, and cost-effective neutron production, facilitating economic use and industrialization, while improving the conversion efficiency of electrons to neutrons.
Smart Images
Figure EP2024076740_03042025_PF_FP_ABST
Abstract
Description
[0001] Title: Device and method for producing
[0002] Neutrons
[0003] Description
[0004] The invention relates to a device for generating neutrons having the features of claim 1 and to a method for generating neutrons having the features of the independent claim.
[0005] Neutrons can be used for experiments in basic research. In large research facilities, neutron sources with particle fluxes in the range of 10 9 up to 10 13Neutrons / s can be achieved. These neutron sources are based in particular on particle accelerators (electrons, protons, deuterons), whose fast particles in turn trigger nuclear processes in the bombarded material, which ultimately results in the emission of neutrons. In the case of electrons, for example, this can be achieved via conversion by means of bremsstrahlung into high-energy photons, which in turn trigger a nuclear reaction in a target material using giant dipole resonance. In particular, the particle accelerators used in this process, which are based on high-frequency technology, require large structures (approximately 100m scale) with correspondingly high costs and, in particular, stationary, location-bound use.
[0006] In Papp, D.; Necas, A. ; Hafz, N.; Tajima, T.; Gales, S.; Mourou, G.; Szabo, G.; Kamperidis, C. Laser Wakefield Photoneutron Generation with Few-Cycle High-Repetition-Rate Laser Systems. Photonics 2022, 9, 826. https: / / doi.org / 10.3390 / photonics9110826 a method is proposed in which an electron beam generated by laser-based acceleration (Laser Wakefield Acceleration - LWFA) can be used to generate neutrons.
[0007] The disadvantage is that high demands are placed on the laser source in particular.
[0008] It is therefore an object of the present invention to provide a device and a method for generating neutrons, wherein the device or method is more efficient, more robust and more cost-effective.
[0009] The above object is achieved by a device for generating neutrons having the features of claim 1. The device comprises a laser source for generating an ultrashort pulse laser beam and a compression device for nonlinear pulse compression of the generated ultrashort pulse laser beam. The device further comprises a beam guiding device for directing, shaping, and / or focusing the compressed ultrashort pulse laser beam. The device also comprises an electron generating device for generating an electron beam by means of laser wakefield acceleration (LWFA). The device further comprises a target for emitting neutrons.
[0010] This allows, in particular, the ultrashort pulse laser source to be made more compact and significantly more cost-effective. The entire device can thus be realized in a significantly more efficient, robust, and cost-effective manner. Economic use, particularly industrialization, of the device for generating neutrons can be realized. A quasi-monoenergetic electron spectrum can be generated, leading to improved electron-to-neutron conversion efficiency.
[0011] According to a further development of the device, the laser source can comprise an ytterbium (Yb)-doped solid-state laser.
[0012] In particular, the wavelength of the ytterbium-doped solid-state laser, which is greater than 1 pm (micrometer), allows for increased efficiency, particularly in the LWFA process. Furthermore, a ytterbium-doped solid-state laser is compact and cost-effective.
[0013] According to a further development of the device, the laser source can be configured to generate an ultrashort pulse laser beam having a pulse duration (or pulse length) in a range of 250 to 850 fs (femtoseconds), a pulse energy in a range of 50 to 1000 mJ (millijoule), and / or a pulse repetition rate in a range of 1 to 100 kHz (kilohertz). This allows the ultrashort pulse laser beam to be optimally adjusted, thus further increasing the efficiency of the device.
[0014] According to a further development of the device, the compression device can comprise at least one multipass cell. The multipass cell can be designed as a Herriott cell. The multipass cell can be gas-filled. The multipass cell can be configured to compress the ultrashort pulse laser beam to a pulse duration in a range of 10 to 50 fs using self-phase modulation.
[0015] In this way, the pulse duration of the ultrashort pulse laser beam can be compressed by simple means to an optimal pulse duration, particularly for the LWFA process, in particular by a compression factor in a range of 10 to 30 times.
[0016] According to a further development of the device, the beam guiding device can have at least one reflective optical element and can be configured to achieve a laser beam diameter (or raw beam diameter) in a range of 10 to 200 mm (millimeters) (1 / e 2 ). Alternatively or additionally, the beam guiding device can be configured to produce a focus with a numerical aperture in a range from 0.02 to 0.2. The value of the numerical aperture can be related to a value in a vacuum, with n=1, where n is the refractive index.
[0017] This allows the compressed ultrashort pulse laser beam to be optimally guided or focused using simple means. According to a further development of the device, the electron generation device can comprise a vacuum chamber. A gas for interaction with the compressed ultrashort pulse laser beam can be provided in the vacuum chamber. The provision of the gas can be implemented in such a way that at the location of the interaction of the compressed ultrashort pulse laser beam with the gas, the gas has an effective particle density in a range of 10 15 up to 10 21 particles / cm 3The gas can be ionized (plasma). The gas can be in the form of a plasma, in particular an optically thin one. The beam guiding device can be configured to focus the compressed ultrashort pulse laser beam into the vacuum chamber, in particular into the gas. The location of the interaction of the ultrashort pulse laser beam with the gas can be the focus of the compressed ultrashort pulse laser beam. Electrons can be generated by means of the compressed ultrashort pulse laser beam, which drives a (non-linear) plasma wave in the ionized gas (plasma).
[0018] This allows the LWFA process to be further optimized using simple means.
[0019] According to a further development of the device, the gas can be formed from pure gas or from a gas mixture. The pure gas can be hydrogen, nitrogen, argon, or helium. The gas mixture can be a gas mixture of different gases, such as helium and nitrogen. This allows a gas or plasma to be provided using simple means, and the LWFA process can be further optimized.
[0020] According to a further development of the device, the electron generating device can be configured such that the (ionized) gas is provided by means of a gas cell or by means of a gas nozzle (gas flame).
[0021] This allows the gas or plasma to be prepared for interaction with the compressed ultrashort pulse laser beam using simple means.
[0022] According to a further development of the device, the electron generating device can be set up in such a way that the generated electron beam in the main peak (main part of the emitted electron beam) has electron energies in a range of 35 to 300 MeV (megaelectronvolts), a spectral half-width of less than 30% of the main peak and / or an electrical charge in a range of 25 to 1000 pC (picocoulombs) per pulse.
[0023] This allows the electron beam to be optimally adjusted so that the efficiency of the device can be further increased.
[0024] According to a development of the device, the target can be designed as a sphere, a hemisphere or a cube. The target can be arranged or positioned in a fixed location. The target can have a thickness in a range from 0.5 to 10 cm (centimeters). The target can have an opening into which the electron beam can be focused. The electrons of the electron beam can interact directly or indirectly with the target or its atoms, so that the target emits neutrons.
[0025] This allows the neutron yield to be increased, so that the efficiency of the device can be further improved.
[0026] According to a further development of the device, the target can be made of (high-purity) tungsten, lead, tantalum, copper, and / or uranium. The target can have a coating. The coating can be made of beryllium deuteride (BeD2). The coating can have a thickness in a range of 1 to 10 cm.
[0027] This allows the conversion efficiency and thus the neutron yield to be further increased, thus further enhancing the efficiency of the device. Target handling can also be improved.
[0028] The above object is further achieved by a method for generating neutrons having the features of the independent claim. The method comprises the steps:
[0029] Generating an ultrashort pulse laser beam.
[0030] Generating a compressed ultrashort pulse laser beam by compressing the ultrashort pulse laser beam using nonlinear pulse compression.
[0031] Shaping, directing, and / or focusing the compressed ultrashort pulse laser beam. Generating an electron beam using laser wakefield acceleration (LWFA).
[0032] Directing the generated electron beam onto a target to produce neutrons .
[0033] This allows for the realization of an efficient, robust, and cost-effective process for generating neutrons. This process can be commercially exploited, particularly for industrialization. A quasi-monoenergetic electron spectrum can be generated, leading to improved electron-to-neutron conversion efficiency.
[0034] According to a further development of the method, in the step
[0035] Generating an ultrashort pulse laser beam, an ultrashort pulse laser beam is generated which has a pulse duration in a range of 250 to 850 fs, a pulse energy in a range of 50 to 1000 mJ and / or a pulse repetition rate in a range of 1 to 100 kHz.
[0036] This allows the ultrashort pulse laser beam to be optimally adjusted so that the efficiency of the procedure can be further increased.
[0037] According to a further development of the method, in the step
[0038] Generating a compressed ultrashort pulse laser beam, the ultrashort pulse laser beam is compressed by means of self-phase modulation to a pulse duration in a range of 10 to 50 fs.
[0039] This allows the pulse duration of the ultrashort pulse laser beam to be compressed to an optimal pulse duration, in particular by a compression factor in a range of 10 to 30 times, using simple means.
[0040] According to a further development of the method, in the step
[0041] Forming the compressed ultrashort pulse laser beam , the beam diameter of the compressed ultrashort pulse laser beam to a beam diameter in a range of 10 to 200 mm ( 1 / e 2 ) can be formed.
[0042] Alternatively or additionally, the step
[0043] Guiding the compressed ultrashort pulse laser beam , the compressed ultrashort pulse laser beam with the beam diameter in a range of 10 to 200 mm ( 1 / e 2 ) .
[0044] Alternatively or additionally, the step
[0045] Focusing the compressed ultrashort pulse laser beam can be performed with a numerical aperture in a range from 0.02 to 0.2. The value of the numerical aperture can be related to a value in a vacuum, with n=1, where n is the refractive index. This allows the ultrashort pulse laser beam to be optimally guided or focused using simple means.
[0046] According to a further development of the method, in the step
[0047] Generating an electron beam , the compressed ultrashort pulse laser beam with a gas with an effective particle density in a range of 10 15 up to 10 21 particles / cm 3 interact. This can be an ionized gas ( plasma ) .
[0048] This allows the LWFA process to be further optimized using simple means.
[0049] According to a further development of the method, in the step
[0050] Generating an electron beam, an electron beam is generated which has electron energies in the main peak in a range of 35 to 300 MeV, a spectral half-width of less than 30% of the main peak and / or an electrical charge in a range of 25 to 1000 pC per pulse.
[0051] This allows the electron beam to be optimally adjusted, further increasing the efficiency of the device. According to a further development of the method, a device as described above can be used to carry out the method.
[0052] With regard to the advantages that can be achieved, reference is made to the relevant explanations of the device. The measures described in connection with the device and / or those explained below can be used to further refine the method.
[0053] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of an embodiment with reference to the drawing. It shows:
[0054] Fig. 1 is a schematic representation of the device.
[0055] The device for generating neutrons 21 is designated overall by reference numeral 10 in Figure 1. The device 10 is shown only schematically.
[0056] The device 10 comprises a laser source 12 for generating an ultrashort pulse laser beam 13. The laser source 12 can comprise an ytterbium-doped solid-state laser or be designed as an ytterbium-doped solid-state laser. The laser source 12 can be configured to generate an ultrashort pulse laser beam 13 having a pulse duration in a range from 250 to 850 fs, a pulse energy in a range from 50 to 1000 mJ and / or a pulse repetition rate in a range from 1 to 100 kHz. The device 10 also comprises a compression device 14 for non-linear pulse compression of the generated ultrashort pulse laser beam 13. The compression device 14 can have at least one, in particular gas-filled, multipass cell. The multipass cell can be configured to compress the generated ultrashort pulse laser beam 13 to a pulse duration in a range of 10 to 50 fs by means of self-phase modulation.
[0057] The device 10 also comprises a beam guiding device 16 for guiding, shaping and / or focusing the compressed ultrashort pulse laser beam 15. The beam guiding device 16 can have at least one reflective optical element. The beam guiding device 16 can be configured to achieve a laser beam diameter in a range of 10 to 200 mm (1 / e 2 ). Alternatively or additionally, the beam guiding device 16 can be configured to produce a focus with a numerical aperture in a range from 0.02 to 0.2 (in a vacuum).
[0058] The device 10 further comprises an electron generating device 18 for generating an electron beam 19 by means of laser wakefield acceleration. The electron generating device 18 may comprise a vacuum chamber. In the vacuum chamber, a gas may be provided for interaction with the compressed ultrashort pulse laser beam 15 such that, at the location of the interaction, the gas has an effective particle density in a range of 10 15 up to 10 21 particles / cm 3The beam guiding device 16 can be set up to focus the compressed ultrashort pulse laser beam 15 into the (ionized) gas of the electron generating device 18, at the location of the interaction. The gas can be made up of pure gas (e.g. helium, nitrogen, argon or hydrogen) or of a gas mixture (e.g. helium and nitrogen). The gas can be provided by means of a gas cell or by means of a gas nozzle. The electron generating device 18 can be set up such that the generated electron beam 19 has electron energies in the main peak in a range from 35 to 300 MeV, a spectral half-width of less than 30% of the main peak and / or an electrical charge in a range from 25 to 1000 pC per pulse.
[0059] The device 10 comprises a target 20 for emitting neutrons 21. The target 20 can be designed as a sphere, a hemisphere or a cube. The target 20 can have a thickness in a range from 0.5 to 10 cm. The target 20 can have an opening into which the electron beam 19 can be focused. The target 20 can be made of tungsten, lead, tantalum, copper and / or uranium. The target 20 can have a coating. The coating can be made of beryllium deuteride. The coating can have a thickness in a range from 1 to 10 cm.
[0060] In the following, a method for generating neutrons 21 is described using the device 10 shown in Figure 1:
[0061] The method comprises the step of generating an ultrashort pulse laser beam 13. In this case, a
[0062] An ultrashort pulse laser beam 13 is generated which has a pulse duration in a range of 250 to 850 fs, a pulse energy in a range of 50 to 1000 mJ and / or a pulse repetition rate in a range of 1 to 100 kHz.
[0063] The procedure also includes the step:
[0064] Generating a compressed ultrashort pulse laser beam 15 by compressing the ultrashort pulse laser beam 13 using non-linear pulse compression. The ultrashort pulse laser beam 13 can be compressed to a pulse duration in a range of 10 to 50 fs using self-phase modulation.
[0065] The procedure further includes the step:
[0066] Shaping, directing and / or focusing the compressed ultrashort pulse laser beam 15. The beam diameter of the compressed ultrashort pulse laser beam 15 can be adjusted to a beam diameter in a range of 10 to 200 mm (1 / e 2) . Alternatively or additionally, the compressed ultrashort pulse laser beam 15 can be formed with a beam diameter in a range of 10 to 200 mm ( 1 / e 2 ) . Alternatively or additionally , the focusing of the compressed ultrashort pulse laser beam 15 can be carried out with a numerical aperture in a range from 0 .02 to 0 .2 .
[0067] The method also comprises the step of generating an electron beam 19 by means of laser wakefield
[0068] Acceleration . The compressed
[0069] Ultrashort pulse laser beam 15 with an (ionized) gas with an effective particle density in a range of 10 15 up to 10 21 particles / cm 3interact. In this case, an electron beam 19 can be generated which has electron energies in the main peak in a range of 35 to 300 MeV, a spectral half-width of less than 30% of the main peak and / or an electrical charge in a range of 25 to 1000 pC per pulse.
[0070] The procedure also includes the step:
[0071] Directing the generated electron beam 19 onto a target 20 to generate neutrons 21. The electron beam can
[0072] 19 through an opening on the target 20 into the interior of the target
[0073] 20 are guided and / or focused. Due to the direct or indirect interaction of the electron beam 19 (or its electrons) with the target 20 (or its atoms), neutrons 21 are emitted from the target 20.
[0074] To carry out the method, a device 10 according to the above statements can be used.
Claims
Patent claims 1. Device (10) for generating neutrons (21) comprising: a laser source (12) for generating an ultrashort pulse laser beam (13), a compression device (14) for non-linear pulse compression of the generated ultrashort pulse laser beam (13), a beam guiding device (16) for guiding, shaping and / or focusing the compressed ultrashort pulse laser beam (15), an electron generating device (18) for generating an electron beam (19) by means of laser wakefield acceleration, a target (20) for emitting neutrons (21).
2. Device (10) according to claim 1, characterized in that the laser source (12) comprises an ytterbium-doped solid-state laser.
3. Device (10) according to claim 1 or 2, characterized in that the laser source (12) is arranged to generate an ultrashort pulse laser beam (13) having a pulse duration in a range of 250 to 850 fs, a pulse energy in a range of 50 to 1000 mJ and / or a pulse repetition rate in a range of 1 to 100 kHz.
4. Device (10) according to one of the preceding claims, characterized in that the compression device (14) has at least one, in particular gas-filled, multi-pass cell in order to compress the generated ultrashort pulse laser beam (13) to a pulse duration in a range of 10 to 50 fs by means of self-phase modulation.
5. Device (10) according to one of the preceding claims, characterized in that the beam guiding device (16) has at least one reflective optical element and is designed to have a laser beam diameter in a range of 10 to 200 mm (1 / e2 ) and / or to produce a focus with a numerical aperture in a range of 0.02 to 0.
2.
6. Device (10) according to one of the preceding claims, characterized in that the electron generating device (18) comprises a vacuum chamber, wherein a gas is provided in the vacuum chamber for interaction with the compressed ultrashort pulse laser beam (15) such that at the location of the interaction the gas has an effective particle density in a range of 10 15 up to 10 21 particles / cm 3 has.
7. Device (10) according to claim 6, characterized in that the gas is formed from pure gas, in particular helium, nitrogen, argon or hydrogen, or from a gas mixture, in particular from helium and nitrogen.
8. Device (10) according to claim 6 or 7, characterized in that the electron generating device (18) is arranged such that the gas is Gas cell or by means of a gas nozzle.
9. Device (10) according to one of the preceding claims, characterized in that the electron generating device (18) is set up such that the generated electron beam (19) in the main peak has electron energies in a range of 35 to 300 MeV, a spectral half-width of less than 30% of the main peak and / or an electrical charge in a range of 25 to 1000 pC per pulse.
10. Device (10) according to one of the preceding claims, characterized in that the target (20) is designed as a sphere, a hemisphere or a cube, in particular wherein the target (20) has a thickness in a range of 0.5 to 10 cm, further in particular wherein the target (20) has an opening into which the electron beam (19) can be focused.
11. Device (10) according to one of the preceding claims, characterized in that the target (20) is formed from tungsten, lead, tantalum, copper and / or uranium, in particular wherein the target (20) has a coating, further in particular wherein the coating is formed from beryllium deuteride and / or has a thickness in a range of 1 to 10 cm.
12. A method for generating neutrons (21) comprising the steps of: Generating an ultrashort pulse laser beam (13); Generating a compressed ultrashort pulse laser beam (15) by compressing the Ultrashort pulse laser beam (13) by means of nonlinear pulse compression; Shaping, directing and / or focusing the compressed ultrashort pulse laser beam (15); Generating an electron beam (19) by means of laser wakefield acceleration, Directing the generated electron beam (19) onto a target (20) to generate neutrons (21).
13. Method according to claim 12, characterized in that in the step Generating an ultrashort pulse laser beam (13), an ultrashort pulse laser beam (13) is generated which has a pulse duration in a range of 250 to 850 fs, a pulse energy in a range of 50 to 1000 mJ and / or a pulse repetition rate in a range of 1 to 100 kHz.
14. Method according to claim 12 or 13, characterized in that in the step Generating a compressed ultrashort pulse laser beam (15), the ultrashort pulse laser beam (13) is compressed by means of self-phase modulation to a pulse duration in a range of 10 to 50 fs.
15. Method according to one of claims 12 to 14, characterized in that in the steps Forming the compressed ultrashort pulse laser beam (15), the beam diameter of the compressed ultrashort pulse laser beam (15) to a beam diameter in a range of 10 to 200 mm (1 / e 2 ) is formed, and / or Guiding the compressed ultrashort pulse laser beam (15), the compressed ultrashort pulse laser beam (15) with the beam diameter in a range of 10 to 200 mm (1 / e 2 ) and / or Focusing the compressed ultrashort pulse laser beam (15), the focusing is carried out with a numerical aperture in a range of 0.02 to 0.
2.
16. Method according to one of claims 12 to 15, characterized in that in the step - generating an electron beam (19) which combines the compressed ultrashort pulse laser beam (15) with a gas having an effective particle density in a range of 10 15 up to 10 21 particles / cm 3 interacts.
17. Method according to one of claims 12 to 16, characterized in that in the step Generating an electron beam (19), an electron beam (19) is generated which has electron energies in the main peak in a range of 35 to 300 MeV, a spectral half-width of less than 30% of the main peak and / or an electrical charge in a range of 25 to 1000 pC per pulse.
18. Method according to one of claims 12 to 17, characterized in that a device (10) according to one of the preceding claims is used to carry out the method.