Here, we report on a study of seed plasmas produced by non-resonant 2.45 GHz microwave heating in Heliotron J, which is useful for plasma start-up by neutral beam injection (NBI) under the conditions of low beam power (<1 MW), low accerelation voltage (<30 kV) and small device size (∼1 m). The pre-ionization technique using the non-resonant heating produced the electron density in the order of 10 17 –10 18 m −3 with the energy exceeds the CII ionization potential (30 eV). The existence of the relativistic electrons, which was essential to produce the seed plasmas, was confirmed experimentally during the pre-ionization phase by the synchrotron radiation and the hard x-ray emission measurements. The production mechanism of the relativistic electrons was considered to be stochastic interactions between the electrons and the microwave-frequency field. By optimizing the additional gas fueling during the microwave launch, a higher seed-plasma density...

中文翻译：

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在Heliotron J中使用非共振微波发射进行NBI等离子体启动的种子等离子体生成的研究

在这里，我们报告了在Heliotron J中由非共振2.45 GHz微波加热产生的种子等离子体的研究，这对于在低束功率（<1 MW）的条件下通过中性束注入（NBI）启动等离子体非常有用，较低的加速电压（<30 kV）和较小的器件尺寸（〜1 m）。使用非谐振加热的预电离技术产生的电子密度约为10 17 –10 18 m -3，能量超过了CII电离电势（30 eV）。相对论电子的存在是产生种子等离子体所必需的，在同步化辐射和硬X射线发射测量中，在预电离阶段已通过实验证实了这一点。相对论性电子的产生机理被认为是电子与微波-频率场之间的随机相互作用。通过在微波发射过程中优化额外的气体燃料供应，可以提高种子等离子密度。