HIGH-ACCURACY TIME-RESOLVED AND SPACE-RESOLVED STARK SHIFT MEASUREMENTS (INVITED)

Stark-shift measurements using emission spectroscopy are a powerful to ol for advancing understanding in many plasma physics experiments. We use simultaneous two-dimensional space- and time-resolved spectra to s tudy the electric field evolution in the 20 TW Particle Beam Fusion Ac celerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a mult iplexed mode that enables recording time-resolved spectra from eight s patial locations on a single instrument. Design optimization and chara cterization measurements of the multiplexed spectrograph properties in clude the astigmatism, resolution, dispersion, and sensitivity. A semi automated line-fitting procedure determines the Stark shift and the re lated uncertainties. Fields up to 10 MV/cm are measured with an accura cy +/- 2%-4%. Detailed tests of the procedure confirm that the uncerta inty in the wavelength-shift error bars is less than +/- 20%. Developm ent of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain three-dimensional space- and time-resolved measurements of the electric and magnetic fie lds is in progress. (C) 1997 American Institute of Physics.