Observation of Electron Temperature and Density Gradients in Volumetric Recombining Plasma Using ECR Linear Plasma Experimental Device NUMBER

Spatial gradients of electron temperature and density along the magnetic field line are directly measured in helium recombining plasma using the linear plasma device NUMBER. In a specific neutral gas pressure range, a steep temperature gradient is observed, with a scale length shorter than the device length. At higher pressures, the sign of electron density gradient reversed from positive to negative, indicating existence of a spatial density peak. Reconstruction of spatial temperature and density profiles indicates that monotonically decreasing temperature and the spatial peak of density along the magnetic field line.