Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-07-17
Abstract： Abstract [Background] Betatrons use magnetic field confinement and induced electric fields to accelerate electron beams, making them move in the accelerator tube and eventually bombard the target to produce X-rays. The intensity and dose rate of X-rays produced by the accelerator are closely related to its magnetic induction intensity. The magnetic induction intensity is affected by many factors such as excitation current, number of coil turns and magnetic pole material. [Purpose] In order to study the influence of permanent magnets on the magnetic field of Betatrons. [Methods] In this study, the Poisson program was used to establish a model and perform simulation analysis. The study found that placing the permanent magnet at the accelerator magnetic pole head position can more effectively enhance the magnetic induction intensity and effectively avoid magnetic leakage compared with other yoke positions. [Results] Specifically, in the accelerator structure, permanent magnets with a thickness of 1 cm, a coercive force of 8.6 kOe, and a remanence of 14.4 kGs were placed symmetrically at the bottom of the upper and lower magnetic pole heads, and the same excitation current was maintained as in the state without permanent magnets after the permanent magnets were added. The results showed that: the magnetic induction intensity at the magnetic pole head position increased by about 18.6%, and the magnetic induction intensity near the electron beam equilibrium orbit increased by about 18.6%. This means that under the same magnetic induction intensity requirements, the addition of permanent magnets can reduce the required excitation current by about 29%, and the symmetrical distribution of permanent magnets has little effect on the horizontal component of the magnetic induction intensity. [Conclusion] In summary, the method of combining permanent magnets with electromagnets can effectively improve the performance of Betatrons.
Keywords Betatron ; permanent magnet; Poisson; magnetic induction intensity
Subjects: Nuclear Science and Technology >> Other Disciplines of Nuclear Science submitted time 2024-07-10
Abstract： [Background] Uranium polymetallic ores are strategic emerging industry minerals, and the quantitative analysis of uranium (U) in ores is a crucial step in the development process of such ores. [Purpose] In this paper, a quantitative analysis of U in uranium polymetallic ores using femtosecond laser-induced breakdown spectroscopy (LIBS) combined with partial least squares regression (PLSR) modeling was conducted. [Methods] Initially, the concentrations of U in six samples were measured by high-purity germanium gamma spectrometer and set as reference values. Then femtosecond lasers were employed to ablate the samples to obtain LIBS spectra. Subsequently, two normalization methods were applied to preprocess the raw spectra, and the impact of the preprocessed spectra on PLS model prediction analysis was compared with that of the raw spectra. Subsequently, the spectral data from five sets of samples were utilized as a training dataset to construct a quantitative model, enabling the analysis and prediction of U concentration in sample 3# [Results] The results indicate that the relative standard deviation (RSD) and mean relative error (MRE) of 10 predicted values for sample 3# are merely 5.94% and 4.73%, respectively. [Conclusions] This demonstrates that the combination of PLSR algorithm and femtosecond LIBS exhibits high analytical accuracy and stability for samples. This finding can provide significant reference for practical applications of femtosecond LIBS technology in the quantitative analysis of U content in uranium polymetallic ores.
Subjects: Nuclear Science and Technology >> Other Disciplines of Nuclear Science submitted time 2024-07-01
Abstract： [Background]: Uranium polymetallic ores are strategic emerging industry minerals, and the quantitative analysis of uranium (U) in ores is a crucial step in the development process of such ores. [Purpose]: In this paper, a quantitative analysis of U in uranium polymetallic ores using femtosecond laser-induced breakdown spectroscopy (LIBS) combined with partial least squares regression (PLSR) modeling was conducted. [Methods]: Initially, the concentrations of U in six samples were measured by high-purity germanium gamma spectrometer and set as reference values, and then femtosecond lasers were employed to ablate the samples to obtain LIBS spectra. Subsequently, two normalization methods were applied to preprocess the raw spectra, and the impact of the preprocessed spectra on PLS model prediction analysis was compared with that of the raw spectra. Subsequently, the spectral data from five sets of samples were utilized as a training dataset to construct a quantitative model, enabling the analysis and prediction of U concentration in sample 3# [Results]: The results indicate that the relative standard deviation (RSD) and mean relative error (MRE) of 10 predicted values for sample 3# are merely 5.94% and 4.73%, respectively. [Conclusions]: This demonstrates that the combination of PLSR algorithm and femtosecond LIBS exhibits high analytical accuracy and stability for samples. This finding can provide significant reference for practical applications of femtosecond LIBS technology in the quantitative analysis of U content in uranium polymetallic ores.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-06-30
Abstract： [Background]: Boron Neutron Capture Therapy (BNCT) is a binary radiation therapy with strong targeting and high energy transfer line density at the cellular scale.It has the advantages of short treatment cycle and minimal damage to surrounding healthy tissues,making it a promising cancer treatment method. [Purpose]: This study aims to design beam shaping assembly(BSA)to make the neutron beam of D-Be neutron source suitable for BNCT and ensure neutron directionality. [Methods]: This article uses Monte Carlo simulation programs GEANT4 and FLUKA to simulate the generation of 9Be(d,n)10B reaction neutron sources and subsequent neutron moderation.A feasible scheme design for BSA was carried out using a 1.45 MeV,30 mA deuterium beam to bombard a 9 μm thin beryllium target,and set a basis BSA model with a cylindrical structure as a whole. [Results]: The results show that using a 45 cm thick BiF3 and 5 cm thick TiF3 combined slowing layer,a 12 cm thick Pb reflector layer,an 11 cm thick Al2O3 supplementary slowing layer,and a 0.1 mm thick Cd thermal neutron absorption layer,the outlet is ensured to γ and fast neutron composition,Φepi/Φth, Φepi/Φfast meets the recommended values of the IAEA. [Conclusions]: This study obtained the neutron spectra and BSA specific design scheme of low-energy deuterium beams and thin beryllium targets,providing data reference for the slowing shaping of neutrons in D-Be neutron sources and supporting subsequent research on D-Be sources.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-06-06
Abstract： [Background]: Boron Neutron Capture Therapy (BNCT) is a binary radiation therapy with strong targeting and high energy transfer line density at the cellular scale.It has the advantages of short treatment cycle and minimal damage to surrounding healthy tissues,making it a promising cancer treatment method. [Purpose]: This study aims to design beam shaping assembly(BSA)to make the neutron beam of D-Be neutron source suitable for BNCT and ensure neutron directionality. [Methods]: This article uses Monte Carlo simulation programs GEANT4 and FLUKA to simulate the generation of 9Be(d,n)10B reaction neutron sources and subsequent neutron moderation.A feasible scheme design for BSA was carried out using a 1.45 MeV,30 mA deuterium beam to bombard a 9 μm thin beryllium target,and set a basis BSA model with a cylindrical structure as a whole. [Results]: The results show that using a 45 cm thick BiF3 and 5 cm thick TiF3 combined slowing layer,a 12 cm thick Pb reflector layer,an 11 cm thick Al2O3 supplementary slowing layer,and a 0.1 mm thick Cd thermal neutron absorption layer,the outlet is ensured to γ and fast neutron composition,Φepi/Φth, Φepi/Φfast meets the recommended values of the IAEA. [Conclusions]: This study obtained the neutron spectra and BSA specific design scheme of low-energy deuterium beams and thin beryllium targets,providing data reference for the slowing shaping of neutrons in D-Be neutron sources and supporting subsequent research on D-Be sources.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-01
Abstract： The Tianhuan One (CAT-1: China Astro-Torus 1) is the first magnetically confined plasma device design in China using a magnetically floating dipole field magnet. According to the overall objectives and parameter design requirements of the CAT-1 device, In this paper, a simplified linear current model is used to analyze and calculate the stability of the floating magnet based on methods such as vector magnetic field, mechanical balance and dynamics. The design parameters of the floating magnet, levitation coil, and TSR (Tilt-Slider-Rotation) coil of the device, such as the overall size, spatial position and layout, current, weight, characteristic stability performance and their relationship are given. The results show that for the CAT-1 device, the optimal value of the levitation coil radius is 1.7 m, and the corresponding current is 3.49 kA for the design goal with a floating magnet current of 5MA and a height of 2.0 m. In order to achieve effective resistance and control of the floating magnet offset movement, the working area near the balance point should be limited to Δ z < 100 mm、er < 50 mm、 α< π/24.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-04-15
Abstract： CAT-1 (China Astro-Torus 1) is a levitated dipole field magnetic confinement device, which mainly used for dipole plasma physics experiments, requiring a central floatin
g superconducting coil to be stably levitated for at least 5hr without cooling or power supply. In this paper, a levitation control system of coupling superconducting levitation coil and floating coil is designed. In order to ensure the stable levitation of 1200 kg, 5 MA floating magnet, Simulink model of the control system is established and simulated. Based on Routh-Hurwitz stability criterion, the influence of PID（Proportion-Integral-Derivative） control strategy on stability control is studied. The selection range of stability control parameters is determined: Under ideal conditions, delay time of the PD（Proportion-Derivative） control system is 0.0463s, rise time is 0.1545s, peak time is 0.6283s, adjustment time is 0.0848s, and overshot δ=1.6. The results show that PID can restore the levitated superconducting ring to the preset balance position in a short time, and the load of the circuit can be greatly reduced by adopting the appropriate starting mode. The results provide key technical support for the design and development of levitated superconducting dipole field devices.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-03-25
Abstract： [Background]: Photonuclear reactions and compact neutron sources have emerged as promising tools for the production of medical isotopes, providing alternatives to conventional reactor-based high-enriched uranium methods. East China University of Technology (ECUT) is currently constructing an electron accelerator-driven photoneutron source(ECANS) for medical isotope production research. [Purpose]: Investigate the photonuclear reaction with 100Mo isotope and utilize the generated neutrons for isotopic production. [Methods]: The study involves analyzing the photonuclear reactions of 100Mo and investigating the neutron spectrum and activation yield of 99Mo within a high purity 100Mo target. Based on this photonuclear source, a new model to produce medical isotopes is established, comprising neutron energy modulation layer and neutron reflection layer. The study calculates the production yields of 99Mo, 177Lu, and 90Y in various natural oxides and assesses the feasibility of using photonuclear sources for medical isotope production. [Results]: The research results demonstrate that photo-nuclear reactions can effectively produce medical isotopes such as 99Mo, 177Lu, and 90Y, with respective activities of 17.4/day, 18.2 Ci/day, and 57.0 Ci/day. And in the high purity 100Mo target, the daily output of 99Mo reaches 54.1 Ci/day. [Conclusions]: The study demonstrates the feasibility of using the photodisintegration reaction of 100Mo as a neutron source for secondary production of medical isotopes. This approach offers the potential to enhance the economic viability of isotope production. The study analyzed the content of radioactive impurities in natural oxides under irradiation conditions, providing preliminary insights for subsequent separation and purification processes. Therefore, this research has certain reference value for the development of tools for radioactive isotope production.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-03-03
Abstract： In response to the requirements of the dipole field plasma physics experiment for（CAT-1: China Astro Torus 1）, the device requires the center floating superconducting coil to be stably suspended for at least 5 hours without cooling and power supply conditions. A suspension control system for the coupling system of the superconducting lifting coil and the center floating coil was designed. To ensure the stable suspension of 1200kg and 5MA suspension magnets, the Simulink model of the control system was established and simulated. Based on the Routh Hurwitz stability criterion, the influence of PID control strategy on stable control was studied, and the range of stable control parameters was determined: when the power response frequency of the driving lifting coil should be greater than 9 Hz, and the error of the output current is less than 0.1%, the most effective control effect of the PD control system under ideal conditions is a delay time of 0.0463 seconds Rise time is 0.1545s, peak time is 0.6283s, adjustment time is 0.0848s, overshoot =1.6. The steady-state error err is less than 0.05mm, indicating that the corresponding frequency of the power supply is greater than 9Hz and the output error is less than 0.05%. The results show that based on PID, the suspended superconducting ring can be placed in the preset position in a short period of time, and under the appropriate starting method, the load of the circuit can be greatly reduced, providing strong support for the technical feasibility of the suspended superconducting dipole field device.
Subjects: Nuclear Science and Technology >> Engineering of Nuclear Power submitted time 2024-02-01
Abstract： Betavoltaic nuclear batteries offer a promising alternative energy source that harnesses the power of beta particles emitted by radioisotopes. To satisfy the power demands of microelectromechanical systems (MEMS), 3D structures have been proposed as a potential solution. Accordingly, this paper introduces a novel 3D 63Ni-SiC-based P+PNN+ structure with a multi-groove design, avoiding the need for PN junctions on the inner surface, and thus reducing leakage current and power losses. Monte Carlo simulations were performed considering the fully coupled physical model to extend the electron–hole pair generation rate to a 3D structure, enabling the efficient design and development of betavoltaic batteries with complex 3D structures. As a result, the proposed model produces the significantly higher maximum output power density of 19.74 µW/cm2 and corresponding short-circuit current, open-circuit voltage, and conversion efficiency of 8.57 µA/cm2, 2.45 V, and 4.58%, respectively, compared with conventional planar batteries. From analysis of the carrier transport and collection characteristics using the COMSOL Multiphysics code, we provide deep insights regarding power increase, and elucidate the discrepancies between the ideal and simulated performances of betavoltaic batteries. Our work offers a promising approach for the design and optimization of high-output betavoltaic nuclear batteries with a unique 3D design, and serves as a valuable reference for future device fabrication.
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