Simultaneous observations of energetic (keV) upstreaming and electrostatic hydrogen cyclotron waves

Abstract

A comparative study of upstreaming energetic ions in the kilovolt energy range and electrostatic hydrogen cyclotron (EHC) waves has been made using the ion mass spectrometer and plasma wave receiver data sets for the first 1200 orbits of the S3‐3 spacecraft. The upstreaming energetic ions and EHC waves are found to coincide in over 90% of the events studied. In addition, both EHC waves and upstreaming ions with energies greater than 500 eV exhibit a lower border in their altitude distribution near 5000 km. The nearly exact correlation suggests either that the upstreaming ions are producing the EHC waves or that the EHC waves are heating the ions. One example of EHC waves and upstreaming energetic ions is analyzed to test the two hypotheses. Evidence that EHC waves are heating ions is presented in the form of conic ion distributions which some theories predict are the consequence of this process. Perpendicular ion heating to at least 6 keV is found to coincide with EHC waves. Evidence that the upstreaming ions are the source of free energy for the EHC waves is presented in the form of an ion distribution function with ∂f/∂ν > 0. However, the stability of that ion distribution function is considered and found to be stable unless other conditions such as filamentation or electron drift are invoked. There also exists the possibility that the source of free energy for EHC waves is drifting thermal electrons. For the one example studied the drifting electron process is consistent with data from the S3‐3 magnetometer. However, it is inconsistent with the S3‐3 electron spectrometer which indicates that the current is carried by keV electrons, not thermal electrons. Consequently, the source of free energy for EHC waves is not yet unambiguously determined.

Laboratory simulation of broadband ELF waves in the auroral ionosphere

“…Each species is assumed to have a Maxwellian velocity distribution in its frame of reference. For decades the instability predicted by this model has been used to interpret and predict the influence of electrostatic ion-cyclotron waves in ionospheric energization processes [Kindel and Kennel, 1971;Palmadesso et al, 1974;Kintner et al, 1979;Yau et al, 1983] and has become known as the CDEIC instability. The IEDD instability mechanism, also capable of exciting current-driven electrostatic ion-cyclotron waves, is believed to be relevant to these energization processes as well [Gangull et al, 1985a].…”

In situ Polar observation of transverse cold‐ion acceleration: Evidence that electric field generation is a hot‐ion finite gyroradii effect

“…The Hultqvist et al review makes no case that the direction of power transfer between ions and waves has been experimentally determined to date, nor does it settle the issue of the origin of the waves themselves. It is thus still conceivable that the observed wave activity is a by-product of some nonresonant process [Kintner et al, 1979;Lennartsson, 1980], one that alters the local ion velocity distribution in an intermittent and irrever-sible fashion. Such processes are mentioned but not discussed in much detail [see also Lundin and Hultqvist, 1989;Hultqvist, 1996].…”

Coherent Ion Acceleration Using Beating Electrostatic Waves

“…The ICRH scheme is also employed in the VASIMR experimental rocket concept [33,34,35]. In addition, ion heating by various electromagnetic and electrostatic instabilities has been observed in the Earth ionosphere [36,37,38,39,40].…”