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Measurement of distribution functions of hydrogen atoms and molecules in a negative hydrogen ion source

负氢离子源中氢原子和分子分布函数的测量

基本信息

批准号：
12680484
负责人：
WADA Motoi
金额：
$ 1.28万
依托单位：
DOSHISHA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12680484/
关键词：
Negative ions Time of flight Velocity distribution functions Gas temperature 水素負イオンイオン源中性粒子 T.O.F.

项目摘要

A device to analyze mass separated time of flight spectrum was assembled for the direct measurement of distribution functions for neutral particles in a negative hydrogen ion source. The velocity distribution function of neutral particles effusing out through a 3 mm diameter hole of a 6 cm diameter, 6 cm long compact ion source showed the evidence of an acceleration due to formation of static shock at ion source pressure greater than 0.6 Pa, and the measurement was made below this critical pressure. The data scattering made the determination of distribution function with enough accuracy, and the temperature was obtained by fitting the measured result to a Maxwellian distribution. By sustaining arc discharges filling deuterium, helium, and Ar gases keeping the discharge voltage constant at 63 V and changing the discharge current up to 5 A, gas heating coefficients of 1.7 Kcm^3/W, 0.6 Kcm^3/W, and 1.9 Kcm^3/W were obtained for the respective gas. Here, deuterium showed reduction in temperature against increase in discharge power after reaching the maximum temperature of 1200 K at 6 W/cm^3 discharge heating density. This is attributable to the reduction in high speed component of deuterium molecules by dissociation, which was confirmed through the reduction in deuterium flux.Through the present measurement, the temperature of the molecules in actual ion sources can be assumed close to 1000 K. The temperature of atomic hydrogen has not been clarified yet due to a noise from residual hydrogen, but an attempt to measure it is still continued.

为了直接测量负氢离子源中中性粒子的分布函数，组装了一套质量分离飞行时间谱分析装置。中性粒子通过直径为6cm、长为6cm的紧凑型离子源的直径为3 mm的孔流出的速度分布函数显示出由于在离子源压力大于0.6Pa时形成静态冲击而加速的证据，并且测量是在该临界压力以下进行的。数据分散使得分布函数的确定具有足够的精度，并且通过将测量结果拟合到麦克斯韦分布来获得温度。通过维持充入氘、氦和氩气体的电弧放电，保持放电电压恒定在63 V，并将放电电流改变到5 A，获得了相应气体的1.7 Kcm^3/W、0.6 Kcm^3/W和1.9 Kcm^3/W的气体加热系数。在此，氘在6 W/cm^3的放电加热密度下达到1200 K的最高温度后，随着放电功率的增加，温度降低。这是由于氘分子的高速成分被离解而减少，这一点通过氘通量的减少得到了证实。通过本测量，实际离子源中分子的温度可以假定接近1000 K。由于残余氢的噪声，原子氢的温度尚未澄清，但仍在继续尝试测量它。