Exposure of vacuum plasma spraying tungsten to PISCES and DIII-D plasmas

The effects of D plasma pre-irradiation of vacuum plasma spraying tungsten (VPS-W), when exposed to He plasma exposures were investigated by using the linear plasma simulator, PISCES-A and the divertor materials evaluation system (DiMES) in DIII-D tokamak. Polished VPS-W samples with and without pre-exposure to 1 × 1026 D/m2 deuterium plasma were loaded into PISCES-A as well as DiMES for He exposure. Scanning electron microscopy (SEM) images show that significant surface morphology changes occur under tokamak condition. Mass loss of the samples is found to be relevant to poloidal loading position in DIII-D, indicating erosion induced by ELMing He plasma exposure. The effects of D pre-irradiation on retention are discussed by comparing results of nuclear reaction analysis (NRA) and thermal desorption spectroscopy (TDS).