Enhancement of the Plasma Potential by Fluctuating Electric Fields near the Ion Cyclotron Frequency

It is found that ion cyclotron resonance frequency can create an ion-plugging plasma potential equal to several times Tₑe(Tᵢe) in the Phaedrus tandem mirror end cells or at the end of the central cell. A model based on a local balance of electron expulsion by the rf field ̃ \~Ez and trapping by Coulomb scattering predicts the magnitude and scaling of the potential with density and rf antenna current. This model is in reasonable agreement with experimental observations. This ion-cyclotron resonance-frequency enhanced potential increases as the plasma density decreases and as the antenna current increases.