Space resolved XUV/VUV spectroscopy of low temperature plasmas

Transmission grating based survey imaging spectrometers in the XUV/VUV have been developed for diagnosing tokamak divertor and edge. The XUV and the VUV spectrometers had moderate spectral resolution ($\lambda/\delta \lambda \sim 30$), but wide spectral range ($30-800$ \AA\ for the XUV, $100-2000$\AA\ for the VUV). The XUV(VUV) spectrometer covered an angular view of $\pm3.5^0$($\pm1.6^0$) with a $0.45^0$($0.2^0$) resolution. These spectrometers were tested on two different low temperature plasma experiments - (a) A Penning ionization discharge (PID) at JHU ($n_e \sim 10^{19}/\textrm{m}^3, T_e \sim 1$eV) and (b) The PISCES-A linear plasma experiment at UCSD ($n_e \sim 10^{18}/\textrm{m}^3, T_e < 6$eV). Distinct radial emission profiles were measured in both the experiments from a variety of ions: H, He, C, Ne and Al. For most ions, higher charge states were observed on the PID than on PISCES-A. For example upto Al$^{+3}$ and Ne$^{+3}$ were observed on the PID and only upto 2 times ionized Al and Ne were observed on PISCES-A. This may be attributed to the presence of non-Maxwellian electrons in the PID. However, the PISCES-A experiment observed up to C$^{+2}$, while only C$^{+1}$ was observed on the PID. This poster will present the experimental spectra and the related modeling.