Rotation experiments at the Plasma Sciences
Laboratory
Plasma rotation experiments focus on :
Measuring the response of the plasma parameters (density,
electron temperature, plasma potential, etc.) as a function of the
rotation speed of the plasma.
Determining the effect of the driven rotation on driven and
self-oscillations of the plasma.
Investigating the different responses of the plasma due to
radially inward and radially outward electric fields.
Rotation of the plasma is achieved by biasing a series of
concentric rings at
the end of the plasma.
Key Observations
Low frequency ( 0.5fci ² f ² 3fci) waves are observed in the plasma. The wave frequency is dependent upon neutral pressure and magnetic field strength.
Wave modes have different growth behaviors as a function of
the bias voltage (current).
There is a zero-order response of the plasma density to the
applied bias voltage on Ring 3.
An example of wave growth / suppression as a function of the bias voltage on the inner rings (1-3 varied, 4 held fixed).
Present experiments are exploring the "transition region" where the waves become highly suppressed in ALEXIS.
