Diagnosis of three dimensional, time varying magnetic fields in plasmas

Measurement of the temporal evolution of magnetic field topologies in three dimensions is of great importance in a variety of problems in plasma physics. These range from the study of tearing modes, which can occur in both extraterrestrial and fusion plasmas, to the fields which surround charged particle beams or current filaments. In some cases detailed in situ measurements are not possible. For example a probe on a satellite samples data at only one position in what is believed to be a complex three dimensional situation, probes in machines with fusion parameters are rapidly destroyed (and in turn destroy confinement). In view of this a large (2 meter length, a meter diameter) plasma source has been constructed at UCLA with parameter (n/sub e/ ≅ 10/sup 12//cm/sup 3/, 1 < T/sub e/ < 10 ev), (T/sub e//T/sub i/) -- 10, 5 -- B/sub o/ ≤ 150 Gauss) which allow for the insertion of probes and antennas through over 30 ports. Magnetic fields are measured with 3 orthogonal small (1 cm diameter, Δr = 1 mm) pick-up loops mounted on a probe drive capable of placing them anywhere within the device volume