Measurements of flow velocity in the plasma generator PSI-2

The plasma flow velocity in the Plasma Generator PSI-2 has been investigate d by using of Mach probe. PSI-2 is a stationary high-current arc discharge in which the quasi-neutral plasma expands along the magnetic field lines. T he low-temperature (T-e < 20 eV), medium density (n(e) similar to 10(18)-10 (19)m(-3)) plasma in the discharge is similar to the plasma in the divertor region of tokamaks. From the ratio of ion saturation currents collected fr om opposite sides of the probe the flow velocities (Mach numbers) in argon and hydrogen discharges are obtained.