Novel gas target for laser wakefield accelerators

Abstract

A novel gas target for interactions between high power lasers and gaseous medium, especially for laser wakefield accelerators, has been designed, manufactured, and characterized. The gas target has been designed to provide a uniform density profile along the central gas cell axis by combining a gas cell and slit nozzle. The gas density has been tuned from ∼10 atoms/cm to ∼10 atoms/cm and the gas target length can be varied from 0 to 10 cm; both changes can be made simultaneously while keeping the uniform gas profile. The gas density profile inside the gas cell has been measured using interferometry and validated using computational fluid dynamics.

Optical diagnostics for density measurement in high-quality laser-plasma electron accelerators

“… Standard TAI , such as Mach–Zehnder interferometers, where the light beam is split into two distinct beams following different geometrical paths, called the reference and measurement arms, which are then recombined and interfere [7, 23, 24] . Modified TAIs , also called two-arm folded, where the light beam is split into two parts after passing through the sample, and interference takes place between the part of the beam that has passed through the sample and the part of the beam not passing through the sample [18, 25] . This method provides good control on the fringe spacing and image formation.…”

“…Standard TAI , such as Mach–Zehnder interferometers, where the light beam is split into two distinct beams following different geometrical paths, called the reference and measurement arms, which are then recombined and interfere [7, 23, 24] .…”

“…In such a case, the plasma length covered by the interferometer light beam lies between (roughly the dimensions of the main laser beam spot) and hundreds of . The transverse neutral gas length can range from mm typical for pulsed jets [17] to tens of millimeters in gas flow cells [21, 24, 54] .…”

Accurate single-shot measurement technique for the spectral distribution of GeV electron beams from a laser wakefield accelerator

“…The design of the gas cell was based on simulations (ANSYS fluent) and generated a uniform plasma density profile. More details about the gas target can be found in 26 . Figure 8; the fringe field continues for several centimeters past the pole edges, and the maximum magnetic field strength corresponds to B = 1.33…”

Summary of laser plasma physics sessions at the first AAPPS-DPP conference

“…In the commissioning experiments, electron beams at ~ 4.5 GeV with an energy spread about 20% was obtained by focusing a positively chirped 30-fs 52-J laser pulse by F/50 spherical mirror on a 7 cm gas medium at the density of 1.5 × 10 18 /cm 3 . The gas medium was designed to be length variable with uniform gas density by combining the advantages of slit nozzle and gas cell, named as "Slitcell" (Aniculaesei et al 2018). The mixed gas will be used to test ionization injection for reduced beam energy spread and higher electron energy over 10 GeV, which can be applied to generate bright gamma rays by Compton backscattering as well as to investigate the strong field QED effects via the laser electron collision.…”