Anomalous electron heating and energy balance in an ion beam generated plasma

The plasma described in this report is generated by a 15 to 34 kV ion beam, consisting primarily of protons, passing through an H2 gas cell neutralizer. Plasma ions (or ion-electron pairs) are produced by electron capture from (or ionization of) gas molecules by beam ions and atoms. An explanation is provided for the observed anomalous behavior of the electron temperature (T/sub e/): a step-lite, nearly two-fold jump in T/sub e/ as the beam current approaches that which minimizes beam angular divergence; insensitivity of T/sub e/ to gas pressure; and the linear relation of T/sub e/ to beam energy