分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: The Dragon-I linear induction accelerator (LIA) at China Academy of Engineering Physics generates 20 MeV flash X-rays mainly for radiography applications in fluid dynamics. Its spectral information is quite important for diagnostic X-ray imaging applications, but because of its short pulse and great radiation intensity, direct measurement is impossible. In this work, we propose a new method based on transmission measurements to obtain the flash X-ray spectrum. Pure iron cylinders were used as attenuation material, and alanine dosimeters were attached on their rear bottom to record the dose after different degrees of attenuation. Iterative least square method was used to unfold the spectrum, while Geant4 Monte Carlo code was used to simulate the X-ray spectrum. The unfolded spectrum and the simulated spectrum have a high degree of consistency, with the reduced chi-square value of 0.044. This shows that the method is reliable in estimating megavoltage high-intensity X-ray spectrum.
分类: 核科学技术 >> 粒子加速器 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Recently we measured with the Modified Three Gradient Method (MTGM) [1, 2] the beam emittance of an injector constructed in 2012, which was designed to provide a 2.4 kA, 2.6 MeV electron beam. The MTGM is a non-intercept indirect method, which is based on the three gradient type measurements of beam profiles and subsequent data processing which helps to get the least square solution to the beam emittance. Beam profiles under different currents of guiding coil are measured using Cerenkov radiation given off by a piece of quartz glass in the beam tube, which is recorded with a CCD camera. MTGM Code is developed to realize the data fitting as well as beam transport simulation, in which both the matrix method and the numerical solution of root-mean-square beam envelope equation are used. The error is also analyzed.
分类: 核科学技术 >> 粒子加速器 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: A cold-cathode Penning Ion Gauge (PIG) type ion source as the internal ion source of an 11 MeV cyclotron is designed and tested at Institute of Fluid Physics. The design considerations and some testings are presented. Experimental results of Balmer-line-Emission show that the discharge characteristic, which is mainly determined by gas-flow rate, is not very sensitive to arc current and magnetic field in the operation ranges of the cyclotron. The arc power decreases and ascends while the gas-flow rate goes up from 0.5 SCCM to 20 SCCM. By improving the sealing design and reducing the machine tolerance of the source, the minimum power consumption reduces from 9 SCCM to 4 SCCM, thus having better energy efficiency and benefiting for the pumping system. Preliminary DC extractions show that H microampere current ranges from several tens to hundreds under different operation conditions. Some problems during the experiments and future plan are discussed in the end.