Accumulation Process of Negative Ions in a Hollow-Type Magnetized Plasma

空心型磁化等离子体中负离子的积累过程

基本信息

批准号：
12680477
负责人：
MIENO Tetsu
金额：
$ 1.98万
依托单位：
Shizuoka 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-12680477/
关键词：
Reactive plasma Accumulation of negative ions Hollow-type magnetized plasma Cylindrical Plasma String-type plasma Carbon fluoride Negative ion beam source Diffusion coefficient 負イオン蓄積拡散系数プラズマプロセッシング

项目摘要

1) A magnetized plasma from CF_4 gas is generated by the electron cyclotron resonance discharge and a follow-type magnetized plasma is produced by use of a disk-type obstacle at the downstream region of the plasma. Inside the hollow-type plasma, fluorine positive and negative ions are accumulated, generating an ion-ion plasma. By means of a probe measurement, the ratio of negative ion density to electron density becomes more than 20. This phenomenon can be explained by a difference of radial diffusion speeds of electrons and negative ions. As the radial direction diffusion speed is decided by the collision frequency with neutral particles and a step length (a Lamor radius), the negative ions have much larger diffusion speed than that of electrons. As a result, positive and negative ions are preferably diffused into the vacuum region inside the hollow plasma. On the other hand, along the line of magnetic field, electron and ions freely move. At the end plates, high energy electrons tend … More s to flow into the plates beyond a barrier of sheath potential. Otherwise, the negative ions are reflected by the sheath barrier potential and well confined between the end plates. By this process, negative ions are effectively accumulated inside the hollow plasma2) By means of a multi-hole type obstacle, a multi-string plasma is produced at the down-flow region of the magnetized plasma from CF_4 gas. In this case, negative ions accumulate around the string plasmas. Here, many string plasmas are generated with same interval and large volume negative-ion accumulation can be produced. As a results, the large area negative ion source with cross-section of 30 cm^2 has been successfully generated. By use of a magnetic filter a negative ion-beam can be extracted from this plasma source and can be used for the large-area negative ion processing and the neutral beam processing.3) By means of a UV-range pulsed laser, amount of negative ions inside the follow plasma is measured and it is compared with the probe data. Less

1)通过电子回旋共振放电产生CF_4气体磁化等离子体，并利用等离子体下游区域的盘型障碍物产生跟随型磁化等离子体，在中空型等离子体内部，氟正离子。负离子聚集，产生离子-离子等离子体，通过探针测量，负离子密度与电子密度之比超过20。这种现象可以通过电子径向扩散速度的差异来解释。由于径向扩散速度由与中性粒子的碰撞频率和步长（拉莫尔半径）决定，因此负离子的扩散速度比电子大得多，因此，正离子和负离子。另一方面，电子和离子沿着磁场线自由移动，在端板处，高能电子倾向于越过势垒流入板中。的鞘电位。负离子被鞘层势垒电势反射，并被很好地限制在端板之间。通过这个过程，负离子有效地积聚在中空等离子体内2)通过多孔型障碍物，在处产生多串等离子体。 CF_4气体的磁化等离子体的下流区域在这种情况下，负离子聚集在弦等离子体周围，从而产生大量的弦等离子体，从而产生大量的负离子积累。大面积负离子源通过使用磁过滤器，可以从该等离子体源中成功地产生横截面为 30 cm^2 的负离子束，并可用于大面积负离子处理和中性束处理。 3) 通过紫外范围脉冲激光，测量后续等离子体内的负离子量，并与探针数据进行比较。