Electron Acceleration in Cavitated Channels Formed by a Petawatt Laser in Low-Density Plasma

Abstract

International audienceThe spectra of energetic electrons produced by a laser interaction with underdense plasma have been measured at intensities >3×10^20 W cm^-2. Electron energies in excess of 300 MeV have been observed. Measurements of the transmitted laser spectrum indicate that there is no correlation between the acceleration of electrons and plasma wave production. Particle-in-cell simulations show that the laser ponderomotive force produces an ion channel. The interaction of the laser field with the nonlinear focusing force of the channel leads to electron acceleration. The majority of the electrons never reach the betatron resonance but those which gain the highest energies do so. The acceleration process exhibits a strong sensitivity to initial conditions with particles that start within a fraction of a laser wavelength following completely different trajectories and gaining markedly different energies

Observation of Betatron X-Ray Radiation in a Self-Modulated Laser Wakefield Accelerator Driven with Picosecond Laser Pulses

“…The measured x-ray spectra are fit with a synchrotron spectrum with a critical energy of [10][11][12][13][14][15][16][17][18][19][20] ::::…”

“…If the laser intensity is increased to above 10 20 W/cm 2 , almost all the electrons are expelled from the focal volume, creating a near hollow channel [18]. The SMLWFA structure no longer exists in this case, and electrons will be accelerated by DLA alone [19] and emit betatron x-rays : x ::::…”

Fast Charged Particles and Super-Strong Magnetic Fields Generated by Intense Laser Target Interaction

“…Threshold smearing evidences for stochastic character of the process. The good agreement between theory and experiment (Matafonov & Belyaev, 2001;Malka & Miquel, 1996;Borodin et al, 2000;Nickles et al, 1999;Ledingham & Norreys, 1999;Cowan et al, 1999;He et al, 2004;Mangles et al, 2005) suggests the realizability of the proposed high-energy electron formation mechanism in laser plasmas. In our article (Belyaev, Kostenko et al, 2003) we also have investigated cyclotron mechanism of electron acceleration.…”

Control of Laser Plasma Based Accelerators up to 1 GeV

“…This operational regime is called the self modulated laser wakefield acceleration (SM-LWFA). Although experiments with such high energy, high power, sub-picosecond Nd:glass based lasers (for example, 250 TW in 650 fs [27], τ L τ p ) are still actively being pursued [27][28][29][30][31][32][33][34][35][36][37][38][39], the majority of research has shifted to experiments with shorter pulse duration (τ P τ L 100 fs), higher repetition rate Ti:Sapphire based CPA laser systems [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55]. Experimental setups for SM-LWFA experiments were simple and similar everywhere.…”