Electron temperature and density distributions of detached plasma in divertor simulation experiments in GAMMA 10/PDX

Spatial characterization of plasma detachment attributed to molecular activated recombination (MAR) has been done by measuring distributions of electron temperature, electron density, space potential and floating potential of divertor simulation plasma in GAMMA 10/PDX tandem mirror with Langmuir probes. As the hydrogen pressure in the divertor simulation experimental module was increased by supplying additional hydrogen gas, the electron temperature near the target decreased from 30 eV to about 2 eV and the electron density first increased to an order of nearly 1017 m−3, and then decreased in contrast to the density measured at the upstream of the target which became saturated. The density decrement was higher near the corner of the V-shaped target although temperature distribution was almost flat near the target. In addition, space potential decreased, floating potential increased, and then the potential difference between those became small. The potential difference decreased to almost zero near the target. In a direction crossing a plasma column along the target, electron temperature decreased with increase in the pressure, keeping its distribution almost flat.