Abstract
Abstract
Recently, a compact torus injection (CTI) system was
developed for central fueling on experimental advanced
superconducting tokamak (EAST). As impurity generated by the
interaction between CTI plasma and the electrode material can dilute
the fuel particle, it is important to measure impurity content in
CTI and evaluate the effect of impurity on the plasma before the
application of CTI to EAST. A vacuum-ultraviolet (VUV) spectrometer
that utilizes a concave holographic grating with
1200 groove mm-1 was developed and installed on EAST-CTI for
impurity emission measurement and transport study. The mainly parts
of the spectrometer are an entrance slit, a concave holographic
grating with 1200 groove mm-1 and a charge coupled device
(CCD). The spectrometer is designed to image the spectra of
50–460 nm by turning the grating. Preliminary experimental results
were obtained from the recent EAST-CTI campaign. Impurity line
spectra from 50 to 460 nm wavelength range were measured and
identified for several impurity species, such as iron, copper,
chromium, oxygen, carbon and fluorine. For example, spectra in the
intervals of 150 nm to 300 nm contained strong Fe lines. Helium
spectra are also measured in the form of He I and He II spectral
lines as helium is the main component of the plasma. The results
show that the VUV spectrometer is capable of measuring impurity
radiations on EAST-CTI and will be a useful tool for impurity
behavior study.