Noncryogenic pellet injector for diagnostic purposes on the RFX reversed field pinch

An impurity pellet injector is being developed for the RFX reversed field p inch (RFP) with three aims: measurement of the pitch of the magnetic field lines, transport studies, and first wall conditioning. The injector uses pn eumatically accelerated metal sabots to launch the pellets. In this way the same barrel can be used for pellets of different sizes, speeds and materia ls. With drive pressures of 1-10 bars, velocities of 50-400 m/s can be obta ined, which, based on code simulations, are adequate for core ablation. The measurement of the internal magnetic field will be done by diagnosing the direction of elongation of the pellet plasmoid using a masked charge couple d device camera capable of acquiring 28 images 40 lines X 1024 pixels each with a maximum sampling rate of 50 kHz. (C) 1999 American Institute of Phys ics. [S0034-6748(99)55801-2].