Long (σz ∼ 500 μm) SLAC electron and positron bunches sent into dense plasmas (ne = 0.6 − 2.3 × 10 cm−3) are subject to a transverse two-stream instability called the self-modulation instability or SMI. We use numerical simulations to show that when the SMI saturates, the wakefield excitation reaches the nonlinear regime of the plasma wakefield accelerator (PWFA). We show that defocused particl...

An analytical model for the self-modulation instability of a long relativistic proton bunch propagating in uniform plasmas is developed. The self-modulated proton bunch resonantly excites a large amplitude plasma wave (wakefield), which can be used for acceleration of plasma electrons. Analytical expressions for the linear growth rates and the number of exponentiations are given. We use full th...

Whether a faster-than-Coulomb collisionless mechanism equilibrates ion-electron plasmas with ions initially much hotter than electrons is a fundamental plasma physics question and important for understanding low-luminosity astrophysical accretion flows. Here we study whether Weibel instabilities driven by proton temperature anisotropy produce such a mechanism. From theory and particle-in-cell s...

High-intensity laser–plasma interaction experiments were performed using high-power laser pulses (greater than 8 TW) at a wavelength of 527 nm. These pulses were focused to intensity greater than 10 W/cm into underdense helium plasma at a density of 5 10 cm . Systematic examination of the forward Raman scattering instability was performed by measuring the spectrum of the forward scattered light...

The proton and electron temperature anisotropies in the solar wind are constrained by the instability thresholds for temperature-anisotropy-driven kinetic plasma instabilities. The modifications to the marginal instability conditions from accounting for the influence of damping connected with the collisional effects in the solar wind plasma are calculated for right- and left-handed polarized pa...

We show that temperature anisotropies induced at a shock can account for interplanetary and planetary bow shock observations. Shocked plasma with enhanced plasma b is preferentially unstable to the mirror-mode instability downstream of a quasi-perpendicular shock and to the fire-hose instability downstream of a quasiparallel shock, consistent with magnetic fluctuations observed downstream of a ...

A generalized Lenard-Balescu theory that accounts for instability-enhanced collective responses is used to calculate the collisional friction between ion species in the plasma-boundary transition region (presheath). Ion-ion streaming instabilities are shown to cause such a strong frictional force that the relative flow speed between ion species cannot significantly exceed the critical threshold...

Spatially, temporally, and angularly resolved collinear collective Thomson scattering was used to diagnose the excitation and damping of a relativistic-phase-velocity self-modulated laser wakefield. The excitation of the electron plasma wave was observed to be driven by Raman-type instabilities. The damping is believed to originate from both electron beam loading and modulational instability. T...

A two-dimensional numerical study of the expansion of a dense plasma through a more rarefied one is reported. The electrostatic ion-acoustic shock, which is generated during the expansion, accelerates the electrons of the rarefied plasma inducing a superthermal population which reduces electron thermal anisotropy. The Weibel instability is therefore not triggered and no self-generated magnetic ...