Enhanced electron yield from laser-driven wakefield acceleration in high-Z gas jets

Abstract

An investigation of the electron beam yield (charge) form helium, nitrogen, and neon gas jet plasmas in a typical laser-plasma wakefield acceleration experiment is carried out. The charge measurement is made by imaging the electron beam intensity profile on a fluorescent screen into a charge coupled device which was cross-calibrated with an integrated current transformer. The dependence of electron beam charge on the laser and plasma conditions for the aforementioned gases are studied. We found that laser-driven wakefield acceleration in low Z-gas jet targets usually generates high-quality and well-collimated electron beams with modest yields at the level of 10-100 pC. On the other hand, filamentary electron beams which are observed from high-Z gases at higher densities reached much higher yields. Evidences for cluster formation were clearly observed in the nitrogen gas jet target, where we received the highest electron beam charge of ∼1.7 nC. Those intense electron beams will be beneficial for the applications on the generation of bright X-rays, gamma rays radiations, and energetic positrons via the bremsstrahlung or inverse-scattering processes.

A laser-plasma accelerator driven by two-color relativistic femtosecond laser pulses

“…The accelerated electron beams exit the vacuum chamber through a 300-μm-thick beryllium window into air and are detected by a calibrated integrating current transformer (ICT) ( 22 ) for monitoring the beam charge. Then, they are dispersed by a 16-cm-long, 1-T dipole magnet and simultaneously recorded on an absolutely calibrated image plate (IP) ( 23 ) and a Gd 2 O 2 S:Tb x-ray fluorescent (DRZ) screen, which is coupled with an intensified charge-coupled device (ICCD) to get the energy spectra, as shown in Fig.…”

Laser wakefield acceleration in Kr–He plasmas and its application to positron beam generation

“…The resolutions of this homemade energy spectrometer system at particular energies, such as 350, 300, 250, 200, 150, 125, 100, 75 MeV, reached 5.05, 5, 4.27, 2.36, 1, 0.75, 0.5, and 0.1 MeV, respectively. The charge of the accelerated electron beams are obtained based to the integrated intensity of the energy spectral image recorded on the ICCD, which was already cross-calibrated by an integrating current transformer in a previous work [29]. A laser interferometry setup involves the Nomarski method was used for the on-line plasma density diagnostics.…”

Control of electron beam energy-spread by beam loading effects in a laser-plasma accelerator

“…A beryllium (Be) window was used to couple the electron beam from the vacuum chamber into the diagnostic system installed in air. A calibrated integrating current transformer (ICT) [35] was used for monitoring the electron-beam charge. An 8 cm×16 cm dipole magnet having 2 cm gap between the poles and an effective magnetic-field intensity of 1 T was used as an electron beam energy spectrometer.…”