1. Transmission grating based XUV imaging spectrometer for W and other high Z emission Space and time resolved spectra from ~20-800 Å Few Å spectral resolution adequate for W continua a/15 spatial resolution Several ms time resolution (ROI mode) Accurate and stable photometric calibration Simple and compact Entrance slit Imaging slit Deepak Kumar for The Johns Hopkins Plasma Spectroscopy Group

2. 335 A: Fe XVI Bright CX signals from Li, C, N, O Traces of Cl Traces of Fe Region of intense beam emission Operation of TGIS on NSTX TGIS plasma axis C 4-3 (CX) TGIS view on NSTX CX lines are observed to peak in the region with high neutral s from beam (shown in blue) Emission from medium Z impurities (Cl/Fe), is broad and extends to the core

3. Spectra from ohmic shot (edge emission) illustrates spatial dependence of impurity density 3

4. Tokamak W spectra incompletely understood W will play critical role in ITER performance (n W < few 10 -5 n e ) XUV W spectrum yet poorly understood, while critical for real-time divertor and main plasma purity control 1010.1 core pedestal edge, divertor W 38-46 (Kr-Ni like) Ok ~ Ok So and so Poor (nm) 5 10 ITER W spectrum (Pütterich et al 2008) W 24-37 (Sn-Rb like) W 3-26 (Lu-Cd like) W 57-65 (F-Cl like) W 47-56 (Ar-Co like)

5. Goals for C-Mod W experiments (nm) Example of FTU W accumulation spectra (T e0 ~600 eV) (nm) #30649 #30651 Some spectra resemble prediction, but large variability in spectral features, shape. Very sensitive to n e, T e. The spectra is inherently messy and models need to be validated. Few Å resolution over ~30-500 Å spectral range is adequate for W XUV spectroscopy. Goal: Use the SPACE and time resolving capability of TGIS to measure W XUV spectra from plasmas with known T e, transport profiles Sn to Cd-like

6. Backup slides

7. Impurity accumulation in the core is clearly observed 7 The radiated power is very high because of impurity accumulation Exposure time of spectra Accumulation in the core