An intense pulsed hard X-ray source based on series diode technology
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摘要: 介绍了利用串级二极管产生高强度脉冲硬X射线的方法及其辐射场参数。以“闪光二号”加速器为平台,通过适应性改造,产生快前沿电压脉冲;研制了两级阻抗1 Ω串级二极管,通过串联分压降低二极管端电压、各级二极管电子束独立打靶在空间叠加形成高强度均匀辐射场。解决了悬浮电极绝缘支撑、二极管阴极均匀发射等技术难题,实现了串级二极管的稳定工作。在总电压约700 kV、电流约310 kA条件下,X射线平均能量87 keV,500 cm2上的平均能注量36 mJ/cm2,剂量均匀性(最大值比最小值)达到2∶1。Abstract: There are formidable difficulties to generate intense pulsed hard X-ray. The lack of high fidelity high fluence X-ray source has become a restriction factor of SGEMP effect research. The method for intense large-area pulsed hard X- ray production by using a series diode and the radiation parameters are presented in this paper. Flash II accelerator was refined to generate a fast rise time voltage pulse, and a two-stage series diode was developed for coupling electrical energy of high-voltage generator to a low endpoint voltage bremsstrahlung diode via two diodes in series. The X-rays generated by each diode added in space to improve intensity. A dynamic support system was invented to solve the insulation problem of the floating electrode and double-ring cathodes were designed to improve emission uniformity. The experimental results show that the two-stage series diode can work stably under ~700 kV voltage and ~310 kA current, the average energy of X rays is 87 keV, and the fluence is about 36 mJ/cm2 over 500 cm2 area with dose uniformity 2∶1 at 5 cm from the last converter.
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表 1 连续5次实验二极管电压电流和X射线参数
Table 1. Experimental data of five consecutive shots
shot No. voltage/
kVcurrent/
kAX ray rise
time/nsFWHM/
nsaverage dose/
rad(Si)average fluence/
mJ·cm−2X ray average
energy/keVuniformity 042 697 302 27.2 55.6 314 36.5 86.7 1.7:1 043 686 314 25.2 52.8 305 35.5 87.8 2.0:1 044 721 334 26.5 60.4 322 37.4 89.6 1.9:1 045 701 307 28.2 58.7 318 37.0 86.7 2.0:1 046 698 308 25.1 52.4 303 35.2 82.1 1.7:1 statistics 701±8 313±9 26.4±1.0 56.0±2.8 312±6.8 36.3±0.9 86.6±1.8 -
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