X-ray tomography systems for observations of the effects of radially sheared electric fields on fluctuations in plasmas

Abstract

Experimental verification of the effects of radially sheared electric-field (or potential) formation in plasmas is one of the most critical issues to understand the physics basis for plasma confinement improvements. In the GAMMA 10 tandem mirror, recent experimental results show shear formation effects on the suppression of not only coherent drift waves but turbulence-like fluctuations without any coherent phasing relation during the ion-confining potential formation period. Contours of the central-cell soft x-ray brightness show spatially and temporally fluctuated structures during a weak sheared period by the use of the 50 channel microchannel plate system. A new x-ray tomography system is developed for analyzing temporally and spatially resolved plasma behavior in the presence or absence of these shear formation effects in GAMMA 10. The system consists of two 48-channel silicon semiconductor detector arrays with different viewing angles. X-ray energy responses of the new detector arrays along with response uniformity of detector channels have been characterized using synchrotron radiation at the Photon Factory.

Electron temperature and density measurements by using the Thomson scattering system in the tandem mirror GAMMA 10

“…The spatial resolution of the interferometer is about 3 cm. In figure 7, we show the output intensity of soft X-ray measurement system which is constructed by a microchannel plate (MCP) and measures from the upper port of 45 degrees against Y axis [14]. We measure the electron temperatures at t = 155.1 ms by YAG-TS system.…”