Time dependent VUV spectra are measured in LHD. CIII, OVI, H Ly_&alpha, NeVII, NeVI, NeV lines are observed. We have analysed VUV spectra for a NBI heated experiment with neon gas puffing which showed radiation collapse and identified the radiation loss impurity ions compared with the radial distribution of bolometer.
CIII line intensity ratios can distinguish ionizing or recombining plasma phases since the intensity ratio of I(117.5nm, 2s2p 3P - 2p2 3P )/I(97.7nm, 2s2 1S - 2s2p 1P) is smaller than one in ionizing plasma and greater than one in recombining plasma. In this shot we found the plasma is always in ionizing phase and temperature changed as follows; Te ~ 40 eV (t = 0.2 - 0.8sec), Te ~ 40 eV -> 20 eV (t = 0.8 - 1.1sec ) Te ~ 3 eV( Max radiation, t =1.3sec), Te drops to 2 eV (t = 1.4 - 1.7sec). We identify 2s - 2p fine structure transition lines from neon L-shell ions as a second order diffraction. Ne VII (6 lines), Ne VI (3 lines), Ne V (6 lines) and Ne IV(3 lines). We calculate the intensities of Ne VII and VI lines by our collisional radiative model. Ion density ratios are derived comparing spectra and calculations. We find ion densities of Ne 6+ about equal to Ne 5+. The absolute neon ion density is derived from charge exchange spectroscopy. The 5249A line ( n = 11 - 10) of Ne X is produced by charge transfer. State - selective charge transfer cross sections to high nl states are important to calculate emission rate coefficients. We derived absolute time dependent radiation loss from impurities from the absolute value of neon ion density and VUV spectra. Assuming ne = 1013cm-3 the radiation loss from neon K-shell ions is 17 KW/m3 at 1 keV and neon L-shell ions gives 72 KW/m3 at 100 eV.
We analyzed impurity spectral emission quantitatively 1) Electron temperature is derived from the intensity ratio of CIII line intensities. 2) Radiation loss sources are identified using spectroscopy and bolometer in the case of radiation collapse caused by neon gas puffing. 3) Time dependent radiation loss of impurity ions are derived from line intensities of impurities. 3) Due to radiation loss by neon L-shell ions, temperature falls from periphery until radiation collapse.