Perpendicular Ion Energy Analyzer for Hot-Ion Plasmas

A miniature analyzer probe is described for measuring the component of the ion energy distribution perpendicular to the confining magnetic field in a hot‐ion plasma. The analyzer employs the magnetic field to exclude electrons due to their small gyroradii. Ions are selectively retarded by a positively biased collector. The limits on the operating regime of this analyzer are calculated. The device is used in the MIX 1 mirror machine where we measure an ion temperature of ∼100 eV and plasma density ≳10¹¹ cm⁻³.