Experiments on Cyclotron Resonance and Nonadiabatic Trapping of Hydrogen Ions in a Mirror Machine

Abstract

Ion cyclotron resonance and nonadiabatic trapping of the hydrogen ions in a mirror machine investigated. A hydrogen plasma (about 10⁸ ions/cm³) diffuses into a magnetic mirror field along the magnetic lines of force and an r.f. electric field of 4.5 Mc/s is applied to the plasma through a pair of plane electrodes at the midplane of the magnetic mirrors.
It is observed that the magnetic moments of the ions are increased nonadiabatically at cyclotron resonance field for the molecular ions (5.8 kgauss) and the atomic ions (2.9 kgauss). The latter is attributed to the harmonic resonance of the molecular ions. Nonadiabatic trapping of the molecular ions in a mirror field is also observed at 5.8 kgauss and 2.9 kgauss. About 15% of the injected ions is reflected from the far mirror field. The most of the ions escape through the far mirror field because the applied r.f. electric field is shielded by the plasma.