The performance of magnetic fusion confinement devices is highly dependent upon the confined plasma behavior near the wall of the vacuum vessel or "edge region" of the plasma. Presently, it is very difficult to measure what is happening in this region. The purpose of this research is to develop an instrument system that will measure plasma behavior in the edge region. The measurement approach to be used employs laser light to excite atoms and ions in the plasma edge. When ions or atoms are excited (raised to higher energy states), they emit light (fluoresce) and return to a lower energy state. Spectral analysis of the light signals from the excited ion or atom can reveal what is taking place and the structure of the turbulent activity. However, the signals must be sufficiently strong to be seen above the electronic noise of the measuring instrument and the background noise of the plasma light. This project will evaluate the ratio of the signal to electronic noise and the ratio of the signal to background plasma light noise. Once these calculations are finished, it will be determined whether the proposed technique of measuring the edge plasma behavior will work or can be made to work. This project will also evaluate the feasibility of applying the proposed technique in the divertor (ash removal) region of fusion devices to investigate plasma turbulence there. In Phase II, an instrument will be constructed that can experimentally demonstrate the plasma turbulence measurement system on an operating fusion confinement device.
Commercial Applications and Other Benefits as described by the awardee:This research will result in a new diagnostic tool that will provide measurements with space and time resolution of ion turbulence in magnetically confined plasmas and aid the development of magnetic fusion as a safe, environmentally acceptable energy source. Other applications will be in manufacturing, materials, electronics, electric power computing, the defense industries, and to the commercial sector where plasma processes are used, such as in the semiconductor industry and environmental monitoring.
