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Clarification of fundamental processes in negative ion plasma

阐明负离子等离子体的基本过程

基本信息

批准号：
14380215
负责人：
WADA Motoi
金额：
$ 3.71万
依托单位：
Doshisha University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Formation and destruction processes of negative ions were studied to clarify the factors affected by plasma-surface interaction at the wall of a plasma source confining a negative ion plasma. Simple dependence of negative ion density upon surface characteristic parameter like work function or tungsten coverage rate was not found obvious, but the negative ion density and/or the VUV spectrum of the light emission from the plasma appeared to be dependent upon plasma volume parameters as well. Electron energy distribution functions, perturbation upon extracted negative hydrogen ion (H^-) current due to laser injection into the ion source extraction region, and transport of perturbed plasma by photodetachement were investigated to clarify the effect of neutral collisions. A precise measurement of electron energy distribution function revealed the high energy component occupied larger portion than the one in a simple Maxwell distribution function. This corresponds to more frequent formation of vibrationally excited hydrogen molecules in the plasma. The collision processes were found influential upon the transport of H^- in hydrogen plasma through two mechanisms. The first is the deceleration of plasma due to neutral collision damping, and the second is an enhanced transport of H^- toward the extraction hole, which is presumed caused by a combination with the local electric field. Velocity distribution functions of neutral hydrogen atoms and molecules were measured by mass separated time-of-flight analysis. When the velocity distribution functions of D_2 molecules were fitted to Maxwell distribution functions, the molecular translational temperature increased with the discharge power up to a critical one, and then decreased against further increase of the power. The above experimental observations should form a set of key components to be taken into account for modeling the atomic and molecular processes in a negative ion containing plasma.

为了阐明限制负离子等离子体的等离子体源壁上等离子体-表面相互作用的影响因素，研究了负离子的形成和破坏过程。负离子密度与表面特征参数如功函数或钨覆盖率的关系不明显，但负离子密度和等离子体光发射的真空紫外光谱似乎也依赖于等离子体体积参数。为了阐明中性碰撞的影响，研究了电子能量分布函数、激光注入离子源引出区域对引出的负氢离子(H^-)电流的扰动以及受扰等离子体的光分离输运。电子能量分布函数的精确测量表明，高能分量比简单的麦克斯韦分布函数所占的比例更大。这对应于更频繁地在等离子体中形成振动激发的氢分子。碰撞过程通过两种机制对氢等离子体中H^-的输运产生影响。第一种是由于中性碰撞衰减引起的等离子体减速，第二种是H^-向引出孔的输运增强，推测这是由于与局域电场的结合造成的。用质量分离飞行时间分析方法测量了中性氢原子和分子的速度分布函数。当D_2分子的速度分布函数符合麦克斯韦分布函数时，分子的平移温度随放电功率的增大而升高，达到临界值后又随放电功率的增大而降低。上述实验观察应该形成一套关键组件，用于模拟含有负离子的等离子体中的原子和分子过程。

项目成果

期刊论文数量（66）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Measurement of electron energy distribution function by a compact electrostatic deflection type energy analyzer

用紧凑型静电偏转型能量分析仪测量电子能量分布函数

DOI：
发表时间：
2002
期刊：
Proceedings of International Symposium on Dry Processes 2002
影响因子：
0
作者：
R.Imai;A.Nakajo;H.Hiramatsu;T.Nishimori;T.Kasuya;M.Wada
通讯作者：
M.Wada

Atomic fraction of hydrogen plasma in a negative hydrogen ion source

负氢离子源中氢等离子体的原子分数

DOI：
发表时间：
2004
期刊：
Review of Scientific Instruments 75
影响因子：
0
作者：
M.Wada;T.Kasuya;H.Takahashi;T.Takemoto
通讯作者：
T.Takemoto

Contribution of wall material to the vibrational excitation and negative ion formation in hydrogen negative ion sources

壁材料对氢负离子源振动激发和负离子形成的贡献

DOI：
发表时间：
2004
期刊：
Review of Scientific Instruments 75
影响因子：
0
作者：
M.Bacal;A.A.Ivanov;Jr.;M.Glass-Maujean;Y.Matsumoto;M.Nishiura;M.Sasao;M.Wada
通讯作者：
M.Wada

H.Takahashi, T.Kasuya, M.Wada: "Transport velocity of dc laser induced photodetached electrons in a H-ion source"Review of Scientific Instruments. Vol.75,5. (2004)

H.Takahashi、T.Kasuya、M.Wada：“H 离子源中直流激光诱导光分离电子的传输速度”科学仪器评论。