Measurement of the magnetic field direction in a plasma by collective scattering with a CO2 laser.

The effect of strongly magnetized electrons on the spectrum of collective electron density fluctuations can be used to measure the magnetic field direction in a plasma with laser light scattering. The application of this method to measure the poloidal field in tokamaks is discussed. It is shown that noncircular beam cross sections will increase the angular resolution without loss in spatial resolution. In experiments to measure the ion temperature this technique results in an increase of scattered power received. The magnetic field direction was measured for the first time in a laboratory plasma using a pulsed CO[sub 2] laser and coherent detection. [ABSTRACT FROM AUTHOR]