Plasma instabilities associated with the injection of artificial ion beams into the ionosphere

Plasma instabilities that result when a heavy ion beam is injected into the F-region ionosphere are studied using linear theory and one-dimensional electrostatic particle simulations. The background plasma model used consists of a relatively cool, collisionless O{dollar}sp+{dollar} dominated plasma with concentrations of light ions H{dollar}sp+{dollar} and He{dollar}sp+{dollar}. The ion beam is taken as homogeneous, and due to its large larmor radius (k{dollar}sbbotrhosb{lcub}rm b{rcub}{dollar} {dollar}gg{dollar} 1), unmagnetized. The beam density is assumed to be on the order of or less than the O{dollar}sp+{dollar} density. The frequency range studied is from the lower hybrid frequency down to the O{dollar}sp+{dollar} gyrofrequency.; Important results from the linear theory are as follows. For beam drift velocities, v{dollar}sb{lcub}rm d{rcub}{dollar}, much larger than the H{dollar}sp+{dollar} thermal velocity, v{dollar}sb{lcub}rm H{rcub}{dollar}, the lower hybrid and ion-ion hybrid instabilities dominate with the lower hybrid instability having the largest growth rate. For drifts on the order of v{dollar}sb{lcub}rm H{rcub}{dollar}, the H{dollar}sp+{dollar} gyroharmonic instabilities dominate with the harmonics near the lower hybrid frequency having the largest growth rates. The O{dollar}sp+{dollar} gyroharmonic instability dominates for drifts on the order of the O{dollar}sp+{dollar} thermal velocity.; The simulation results show that for v{dollar}sb{lcub}rm d{rcub}{dollar}/v{dollar}sb{lcub}rm H{rcub}{dollar} {dollar}geq{dollar} 1, the perpendicular H{dollar}sp+{dollar} heating is more efficient than the perpendicular O{dollar}sp+{dollar} or parallel electron heating. At low beam densities, only H{dollar}sp+{dollar} is heated, but as the density is increased, the waves grow to large enough amplitudes to trap and heat the O{dollar}sp+{dollar} and electrons. The wave amplitudes begin to decrease for propagation angles larger than (m{dollar}sb{lcub}rm e{rcub}{dollar}/m{dollar}sb{lcub}rm o{rcub}{dollar}){dollar}sp{lcub}1/2{rcub}{dollar} which results in comparable O{dollar}sp+{dollar} and electron heating.; In the high beam temperature regime, T{dollar}sb{lcub}rm b{rcub}{dollar} {dollar}gg{dollar} T{dollar}sb{lcub}rm o{rcub}{dollar}, T{dollar}sb{lcub}rm H{rcub}{dollar}, T{dollar}sb{lcub}rm e{rcub}{dollar}, the beam thermalization is small in comparison to that of the background particles and background particle heating can be a competing saturation mechanism with beam heating. The beam slow down is typically small in this regime as well. For the case T{dollar}sb{lcub}rm b{rcub}{dollar} {dollar}simeq{dollar} T{dollar}sb{lcub}rm o{rcub}{dollar}, T{dollar}sb{lcub}rm H{rcub}{dollar}, T{dollar}sb{lcub}rm e{rcub}{dollar}, beam trapping is the dominant saturation mechanism.; The results of the linear theory and simulations are compared to observations made during ion beam injection experiments performed aboard sounding rockets. The comparisons show very favorable agreement.