Statistical analyses of a high-energy ion transport on GAMMA 10/PDX

A collisionless plasma with ion temperature perpendicular to a field line of several keV is produced by ion cyclotron heating and confined in a mirror filed on GAMMA 10/PDX. High-energy ions transported along the field lines, which are dropped into a loss cone region in velocity space, are directly measured by several ion detectors at the machine end. These characteristics offer an excellent experimental environment for the study of wave particle interaction in velocity space. Ion detectors equip a semiconductor or a micro-channel plate with a pre-amplifier, which convert an ion charge to a detectable current. The detection energy of ions can be varied by a cylindrical ion energy analyzer or multi-grid electrostatic analyzer. Some intermittent and/or periodic behavior has been observed in detected ion current signals. The ion flux is not only a function of the mirror confined plasma density but also a function of characteristics of several waves and fluctuations. Statistical analyses are applied, and statistical characteristics hidden in a mirror trapping of high-energy ions is discussed.