Development of Measurement Methods of Electric Fields in Plasma Using Laser Spectroscopy

等离子体中的电场测量方法有三个主要局限性，这阻碍了它们在实际放电中的应用。它们是：(1)应用的物质；(2)可测量的电场检测下限；(3)碰撞诱导的激光诱导荧光中的可测量的放电压力。本研究是在1998-1999财政年度进行的，在克服这些限制方面取得了很大进展，具体如下1。这项研究最大的成就是证明了通过比较理论计算的斯塔克分布和实验的斯塔克分布，特别是关于电场存在下光学禁线的光谱外观及其位置，来推导任何物种的电场的能力。讨论了决定可测电场上下限的主要因素，并通过选择高激发里德堡能级，证明了将电场测量精度降低到1V/mm是可能的。为了克服这种压力限制，提出了两步激光诱导荧光(TSLIF)方案，并对其电势进行了实验验证。此外，利用建立的方法对放电等离子体鞘内电场进行了测量，并对其结构进行了定量讨论。并讨论了将这些方法应用于高温等离子体的可能性。

There were three major limitations of electric field measurement methods in plasmas, which have prevented their use in practical discharges. These are, (1) species to be applied, (2) measurable lower detection limits of electric fields, and (3) measurable discharge pressures in collision-induced LIF. By the present study carried out in the fiscal years 1998-1999, there have been great progressives in overcoming each of these limitations as follows.1. The biggest achievement of the study is to have demonstrated the ability to deduce electric fields of any species, by comparing theoretically calenlated Stark profiles and experimental ones, in particular about the spectral appearances and their positions of optically forbidden lines under the presence of electric field.2. The main factors which decides the upper and lower limits of measurable electric fields have been discussed, and by choosing highly excited Rydberg levels, it has been shown that electric field measurements down to 1V/mm be possible.3. In order to overcome the pressure limitations, the scheme of two step laser induced fluorescence (TSLIF) was proposed, and its potential has been experimentally demonstrated.In addition, electric fields in sheath of discharge plasmas has been measuring using these established methods and its structure has been quantitatively discussed. Also, possibilities of applying these methods to high temperature plasma have been discussed.