Measurement of Density Profiles with Pressure in MAP-II and DiPS Linear Devices

Radial profiles of plasma density and electron temperature have been measured by a fast-scanning probe (FSP) system with various neutral pressures in the MAP-II and DiPS linear devices for the divertor simulation. The probe system is made of three probe tips, two of which is for a Mach probe consisting of two opposite-directional probes, and one is for an emissive probe installed on the pneumatically driven fast-scanning system with stroke of 30 cm. In MAP-II, density at the center has been varied from 1.5 × 10¹³ cm^-3 to 0.7 × 10¹³ cm^-3 with pressures of 5.5 to 112 mtorr, while that of DiPS varied from 3.5 × 10¹² cm^-3 to 9 × 10¹² cm^-3 with pressures of 0.8 to 50 mtorr. Relation of density profile with the working pressure/magnetic field is analyzed by using a simple fluid model. Electron temperature at the center is also measured by the Thomson scattering method and compared with those of FSP, which is varied from 0.6 to 6.5 eV