Feedback control of important plasma instabilities

Some of the important residual instabilities of Tokamak and Tandem Mirror fusion devices are trapped particle modes. We discuss control schemes for these instabilities using a Langmuir probe sensor and a Langmuir probe or a pair of electrostatic plates as a suppressor in the low temperature plasma of Linear Machines. We describe a remote suppressor of modulated neutral beam which appears to be highly promising in the context of high temperature fusion plasma of Tokamak and Tandem Mirror reactors.