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The Balmer line profiles of nonradiative supernova remnant shocks provide the means to measure the post-shock proton velocity distribution. While most analyses assume a Maxwellian velocity distribution, this is unlikely to be correct. In particular, neutral atoms that pass through the shock and become ionized downstream form a nonthermal distribution similar to that of pickup ions in the solar wind. We predict the H alpha line profiles from the combination of pickup protons and the ordinary shocked protons, and we consider the extent to which this distribution could affect the shock parameters derived from H alpha profiles. The Maxwellian assumption could lead to an underestimate of shock speed by up to about 15%. The isotropization of the pickup ion population generates wave energy, and we find that for the most favorable parameters this energy could significantly heat the thermal particles. Sufficiently accurate profiles could constrain the strength and direction of the magnetic field in the shocked plasma, and we discuss the distortions from a Gaussian profile to be expected in Tychos supernova remnant.
We present techniques to perturb, measure and model the ion velocity distribution in an ultracold neutral plasma produced by photoionization of strontium atoms. By optical pumping with circularly polarized light we promote ions with certain velocitie
The collision frequencies of electron-neutral-particle in the weakly ionized complex plasmas with the non-Maxwellian velocity distributions are studied. The average collision frequencies of electron-neutral-particle in the plasmas are derived accurat
The velocity distribution function of dark matter particles is expected to show significant departures from a Maxwell-Boltzmann distribution. This can have profound effects on the predicted dark matter - nucleon scattering rates in direct detection e
We present the first laboratory observations of time-resolved electron and ion velocity distributions in forming, magnetized collisionless shocks. Thomson scattering of a probe laser beam was used to observe the interaction of a laser-driven, superso
The irradiation of few nm thick targets by a finite-contrast high-intensity short-pulse laser results in a strong pre-expansion of these targets at the arrival time of the main pulse. The targets decompress to near and lower than critical densities p