利用脉冲衰荡光谱法对基于永久磁铁的螺旋波离子源（HELEN）中的氢负离子密度进行定量分析。

Quantification of atomic hydrogen anion density in a permanent magnet based helicon ion source (HELEN) by using pulsed ring down spectroscopy.

作者信息

Mukhopadhyay D, Pandey A, Bandyopadhyay M, Tyagi H, Yadav R, Chakraborty A

机构信息

Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India.

ITER-India, Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India.

出版信息

Rev Sci Instrum. 2019 Aug;90(8):083103. doi: 10.1063/1.5093914.

DOI:10.1063/1.5093914

PMID:31472659

Abstract

In the present work, a permanent magnet-based helicon plasma source (HELEN) is characterized as a negative ion source. A noninvasive diagnostic technique based on cavity ring down spectroscopy (CRDS) is developed to measure the line-integrated negative hydrogen ion (H) density in HELEN. This paper discusses the experimental results in which negative hydrogen ion density is measured for different magnetic field, pressure, and RF (13.56 MHz) power configurations. It is observed that in high power range (800-850 W), the source is operating in helicon wave heating mode with a background plasma density of ∼10 m and electron temperature of ∼2 eV. Negative hydrogen ion density is measured by CRDS method and also by optical emission spectroscopic technique. The measured negative ion density is in the range of ∼10 m under volume mode operational condition even without any use of standard magnetic filter or cesium seeding in the downstream region. The influence of pressure variation (pressure range from 4 × 10 mbar to 4 × 10 mbar) on negative ion density production is not significant, except for a particular axial magnetic field configuration (55 G) and at 8 × 10 mbar pressure, where ∼34% hike is observed.

摘要

在本工作中，一种基于永磁体的螺旋波等离子体源（HELEN）被表征为一种负离子源。开发了一种基于腔衰荡光谱学（CRDS）的非侵入性诊断技术，以测量HELEN中的线积分负氢离子（H⁻）密度。本文讨论了针对不同磁场、压力和射频（13.56 MHz）功率配置测量负氢离子密度的实验结果。观察到在高功率范围（800 - 850 W）内，该源以螺旋波加热模式运行，背景等离子体密度约为10¹⁸ m⁻³，电子温度约为2 eV。通过CRDS方法以及光发射光谱技术测量了负氢离子密度。即使在下游区域未使用任何标准磁过滤器或铯注入的情况下，在体积模式运行条件下测得的负离子密度范围约为10¹⁸ m⁻³。压力变化（压力范围从4×10⁻⁶ mbar到4×10⁻⁵ mbar）对负离子密度产生的影响并不显著，除了一种特定的轴向磁场配置（55 G）以及在8×10⁻⁶ mbar压力下，在该情况下观察到约34%的增长。