Experiment and analysis on mathematical model of 1 MV rod pinch diode
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摘要: 阳极杆箍缩二极管（RPD）具有小焦斑、高亮度的特点，是闪光X光机领域的研究热点。基于Marx发生器和脉冲形成线技术路线产生1 MV高电压脉冲驱动RPD，开展了不同结构参数二极管实验研究。基于RPD物理过程的数值模型，分析了结构参数对箍缩物理过程的影响。研究表明在1 MV电压下，RPD阴极等离子体平均扩散速度、阳极等离子体平均扩散速度分别为2，0.6 cm/μs时，该模型可以较好地描述实验结果。在阳极杆直径一定的情况下，二极管数值模型表明减小阴极孔径可以使二极管更快进入强箍缩状态，但过小的阴极孔径会导致二极管间隙过早闭合。Abstract: Rod pinch diode (RPD) has the characteristics of small focal spot and high brightness, which is a research hotspot in the field of flash radiography. In this paper, based on the Marx generator and pulse forming line technology route, 1 MV high voltage pulse driving RPD is generated, and the experimental research of diode with different structure parameters is carried out. Based on the numerical model of RPD physical process, the ratio of cathode to anode aperture is a complex variable related to the average diffusion velocity of cathode and anode plasma, which is also the main parameter affecting the radiation performance of RPD. The results show that the average diffusion velocity of RPD anode plasma is about 0.6 cm/μs at 1 MV voltage. When the anode rod diameter is fixed, the diode numerical model shows that reducing the cathode aperture can make the diode enter the strong pinch state faster, but too small cathode aperture will lead to premature closure of the diode gap.
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Key words:
- flash radiography /
- flash X-ray generator /
- rod pinch diode /
- numerical model
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图 4 RPD实验和计算结果比较
Figure 4. Waveforms of RPD experiments and calculation with various parameters
表 1 实验结果
Table 1. Results of experiments
type 2rc/mm 2ra/mm Lrod/mm pinch time/ns pulse width of Vd/ns coupling energy/kJ dose@1 m/R a 4.5 1.5 10 35 120 2.75 0.83 b 9.0 1.5 10 50 160 2.85 0.93 c 15.0 1.5 10 80 190 3.15 0.98 d 19.0 1.5 10 105 190 2.52 0.79 
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