Spectroscopic Measurements of Turbulent Electric Fields in An Intense Relativistic Electron Beam-Plasma System

点击翻译按钮获取中文摘要

The main purpose of this research project was to establish spectroscopic methods for measurements of turbulent electric fields in an intense relativistic electron beam-plasma system. Followings are summary of results obtained: 1. An 8-channel spectroscopic system composed of a 0.5 m Ebert-type monochromator(Jarrell-Ash), a rod lens, a fiber bundle and eight photomultipliers has been prepared. Resolution of each channel is 0.03 nm and the minimum separation between neighboring channels is 0.04 nm. 2. Forbidden lines 447.0 nm and 667.8 nm were observed near He I 447.2 nm and 492.2 nm lines, respectively, when an intense beam was injected into a plasma produced in helium gas of 20 m Torr by a pair of plasma guns. The appearance of forbidden lines is an evidence of the turbulent state of the plasma. 3. It was found from Stark shift measurements that there were electric fields even as high as 110-125 kV/cm, and that the distribution of the electric fields was a Gaussian. 4. The turbulent state continued to exist even about 1 mus after the beam ceased to propagate. 5. The results of spectroscopic measurements may be explained by the recently proposed two-component model which states that there are many cavitons in the plasma which repeat creation by nucleation, collapse and burn out, and that the turbulent state consists of cavitons and background weak waves. 6. A N_2-laser for pumping a dye laser was fabricated. The dye laser is to be used for a plasma satellite method with laser induced florescence. 7. When the ratio of the beam electron density and the plasma electron density was higher than about 0.01, high-power broadband microwaves were emitted, and current enhancement phenomenon appeared. However, there was no dependence on this density ratio of the results of the spectroscopic measurements.