Core tungsten radiation diagnostic calibration by small shell pellet injection in the DIII-D tokamak.

Injection of small (outer diameter = 0.8 mm) plastic pellets carrying embedded smaller (10 µg) tungsten grains is used to check calibrations of core tungsten line radiation diagnostics in support of the 2016 tungsten ring campaign in the DIII-D tokamak. Observed total brightness (1 eV-10 keV) and soft x-ray (1 keV-10 keV) brightness are found to be reasonably well (

Experimental characterization of the stagnation layer between two obliquely merging supersonic plasma jets.

We present spatially resolved measurements characterizing the stagnation layer between two obliquely merging supersonic plasma jets. Intrajet collisionality is very high, but the interjet ion-ion mean free path is of the order of the stagnation layer thickness of a few centimeters. Fast-framing camera images show a double-peaked emission profile transverse to the stagnation layer, with the central emission dip consistent with a density dip in the interferometer data. We demonstrate that our observations are consistent with collisional oblique shocks.