[1] We describe the statistical properties of narrowband drifting auroral kilometric radiation (''striated'' AKR) based on observations from the Cluster wideband receiver during [2002][2003][2004][2005]. We show that the observed characteristics, including frequency drift rate and direction, narrow bandwidth, observed intensity, and beaming angular sizes are all consistent with triggering by upward traveling ion solitary structures (''ion holes''). We calculate the expected perturbation of a horseshoe electron distribution function by an ion hole by integrating the resonance condition for a cyclotron maser instability (CMI) using the perturbed velocity distribution. We find that the CMI growth rate can be strongly enhanced as the horseshoe velocity distribution contracts inside the passing ion hole, resulting in a power gain increase greater than 100 dB. The gain curve is sharply peaked just above the R-mode cutoff frequency, with an effective bandwidth 50 Hz, consistent with the observed bandwidth of striated AKR emission. Ion holes are observed in situ in the acceleration region moving upward with spatial scales and speeds consistent with the observed bandwidth and slopes of SAKR bursts. Hence we suggest that SAKR bursts are a remote sensor of ion holes and can be used to determine the frequency of occurrence, locations in the acceleration region, and lifetimes of these structures.

Silicon is rapidly etched by the gas-phase halogen fluorides ClF3, BrF3, BrF5, and IF5, in analogy to XeF2 etching silicon. Nearly complete selectivity over SiO2 is achieved in all cases. By contrast, ClF and Groups III and V fluorides such as NF3, BF3, PF3, and PF5 do not spontaneously etch either Si or SiO2 under the same experimental conditions. These relatively inexpensive interhalogens can be applied to pattern silicon and more generally to remove silicon or polysilicon layers without a plasma. Low-temperature plasmaless gasification of substrates by these fluorine-containing interhalogens is an economically attractive alternative to fluorine-based plasma etching.

Oxidative species produced in a microwave discharge ( 3P2,1O and 1normalΔ O2 ) have been detected, and some of their reactions with organic solids characterized using a gas phase electron paramagnetic resonance (EPR) spectrometer assembled for that purpose. It has been shown that O atoms rather than excited‐state oxygen molecules are the primary reactive species responsible for removal. Also, the O atom oxidation of phenolformaldehyde polymers and graphite has been investigated. The recombination kinetics of O atoms in this flow system can be described by an exponential decay equation involving both wall‐ and gas‐phase collisional recombinations. This allows the signal observed downstream of the reaction to be interpreted as an indication of the gas‐solid reaction rate and thus allows the determination of the activation energies of removal of photoresist (0.5 eV) and graphite (0.45 eV). These experiments have established EPR as a useful analytical tool in the development of gaseous cleaning and other, analogous processes, such as etching.

[1] We investigate waves observed by the Cluster wideband instrument (WBD) during an orbital conjunction with the Polar spacecraft. During this perigee pass, Polar was at the upper extent of the auroral kilometric radiation (AKR) source region in the Southern Hemisphere nightside auroral region. Cluster was located at higher altitude above this region and observed AKR with clear signatures of ordered fine structure striations (rain). Using electron particle data observed by HYDRA on board Polar, we have modeled the electron distribution function within the AKR source region. This distribution function is unstable to a number of low-frequency wave modes and supports EMIC waves propagating along the magnetic field line. These waves appear to be feasible to stimulate the growth of AKR, producing the ordered fine structure observed by WBD on board Cluster, but further analysis will be important, especially plasma simulations.

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