Effective production of gammas, positrons, and photonuclear particles from optimized electron acceleration by short laser pulses in low-density targets

Abstract

Electron acceleration has been optimized based on 3D PIC simulations of a short laser pulse interacting with low-density plasma targets to find the pulse propagation regime that maximizes the charge of high-energy electron bunches. This regime corresponds to laser pulse propagation in a self-trapping mode where the diffraction divergence is balanced by the relativistic nonlinearity such that relativistic self-focusing on the axis does not happen and the laser beam radius stays unchanged during pulse propagation in a plasma over many Rayleigh lengths. Such a regime occurs for a nearcritical density if the pulse length considerably exceeds both the plasma wavelength and the pulse width. Electron acceleration occurs in a traveling cavity filled with a high-frequency laser field and a longitudinal electrostatic single-cycle field ("self-trapping regime"). Monte Carlo simulations demonstrated a high electron yield that allows an efficient production of gamma radiation, electronpositron pairs, neutrons, and even pions from a catcher-target.

Laser-based photonuclear production of medical isotopes and nuclear waste transmutation

“…In this paper, we study nuclear reactions of interest to medical isotope production and the transmutation of long-lived fission products (LLFPs) based on bremsstrahlung gammas produced from the electron accelerated in the RST regime of laser pulse propagation in near-critical density plasma [19,20]. This naturally complements our previous studies of the laser-induced photonuclear processes of neutrons, pairs, and light meson generation [14]. The proposed scheme of production of nuclear isotopes is shown in figure 1.…”

“…The x-ray and gamma ray sources based on LWFA (laser wake field acceleration) [1,2] have numerous potential practical applications in the nuclear field [2][3][4][5], such as medical isotope production [3,[6][7][8], nuclear waste transmutation [9][10][11][12], neutron and light elementary particlegeneration [13,14], and shielded radiography [15][16][17]. Many of these applications rely on the effect of photonuclear cross section enhancement in the vicinity of the giant dipole resonance (GDR) [5], which has a maximum from several MeV to a few tens of MeV.…”

“…It provides a record number of laser accelerated high-energy electrons with only 4 J of laser pulse energy. This also makes it possible to produce a record flux of bremsstrahlung gammas with a multi-MeV energy of quanta [14,17].…”

Experimental Study of the Interaction of a Laser Plasma Flow with a Transverse Magnetic Field

“…As an example, one can note the problem of creating a terahertz using a magnetized wakefield wave [5][6][7][8][9][10], where the sharp boundary between the plasma and free space is required for efficient generation of terahertz radiation. Another example can be the problem of propagation of high-power femtosecond laser pulses in the near-critical plasma in the self-trapping regime [38,39], which is accompanied by efficient generation of high-charge electron beams and hard betatron radiation. Experimental realization of this regime of the interaction of laser radiation with plasmas requires that the laser pulse should be focused on the sufficiently sharp plasma boundary.…”

Bright synchrotron radiation from relativistic self-trapping of a short laser pulse in near-critical density plasma

“…9 in Ref. [25]). The total instantaneous radiated power can be calculated by the relativistic generalization of Larmor's formula [26]:…”