Neutral Beam Injection for the Doublet III Device

Neutral beam injection into Doublet III has been considered with regard to the calculation of non thermalizing particle orbits and the confinement of such orbits. Injected particle loss, based upon these orbits, toroidal gyro-radius effects, and plasma transparency, is calculated to be on the order of 5 percent for coinjection. Near-perpendicular injection at 80 keV has been chosen with the resulting available injection window of 1014 cm-3 ⩽ n(0) ⩽ 3 × 1014 cm-3. Injection into plasmas with n(0) ⩽ 1014 cm-3 will yield large losses due to the increasing transparency of the plasma, whereas injection into plasmas with n(0) ⩾ 3 × 1014 cm-3 shifts the deposition profile toward the plasma edge.