Betatron x-ray radiation in the self-modulated laser wakefield acceleration regime: prospects for a novel probe at large scale laser facilities

Abstract

This paper presents an experimental and theoretical study of betatron x-ray radiation from laser wakefield acceleration in the self-modulated regime. Our experiments use picosecond duration laser pulses up to 150 J, for plasmas with electronic densities on the order of 1019 cm−3. In the self-modulated regime, electrons accelerated in the wake of the laser pulse are subject to both the longitudinal plasma and transverse laser electrical fields. As a result, they undergo oscillations and radiate a synchrotron-like spectrum. In our experimental configuration, electrons accelerated up to about 300 MeV, as well as betatron x-ray spectra with energies of 10 s of keV and photon fluxes between 108–1010 photons/eV/Sr are reported. Our experiments open the prospect of using betatron x-ray radiation for applications, and the source could be competitive with current x-ray backlighting methods on multi-kilojoule laser systems used for high energy density or fusion sciences.

Performance Study on a Soft X-ray Betatron Radiation Source Realized in the Self-Injection Regime of Laser-Plasma Wakefield Acceleration

“…In conditions of direct laser-electron interaction, the critical energy may be even shifted towards γ-rays [30,37,38]. With comparable laser intensity but different systems with longer pulses, different regimes have been studied, as the self-modulated regime [39], demonstrating large photon number and critical energies on the tens of keVs. Further enhancing techniques for photon number and critical energy are based on the addition of wiggling sources and/or density tailoring [31,32,[40][41][42][43][44][45] or with different gas targets [46,47].…”

Planetary physics research at the Facility for Antiprotons and Ion Research using intense ion beams

“…Similarly, betatron radiation produced from ultra-intense short-pulse lasers in a gas jet has a high diagnostic potential due to the small source size, high directionality, and short duration. However, even at laser intensities greater than 10 19 W/cm 2 most of the betatron radiation is concentrated in the spectral range of 10-30 keV [67]. Given the manifold compression reached in the LAPLAS scheme, reducing the target length as investigated in this study would significantly increase transmission at these lower photon energies and thereby help to relax the requirements on the X-ray source.…”

Tomographic characterization of gas jets for laser-plasma acceleration with increased sensitivity

“…It is characterized by a very short pulse duration (~ fs), a small source size (~m), and a very high peak brightness. With these unique properties, the betatron source is an integral part of several high-power laser facilities around the world [3]- [8] for applications ranging from high-resolution radiography [9]- [10], to time-resolved measurements of a dynamical shock wave in a matter [11] and warm dense matter (WDM) [12]. The LPA uses supersonic gas jets (He, He/N2, dry air, or gas clusters [13]- [16]) as targets for the generation of accelerated electron bunches.…”