Generation of short pulse radiation from magnetized wake in gas-jet plasma and laser interaction

Abstract

New features of a high power tunable radiation from the magnetized plasma wakes are studied. This Letter covers some aspects of the problem, which was previously discussed in details in [Phys. Rev. E 68 (2003) 026409]. A gas-jet flow is used to generate the sharp boundary plasma. Wakefield is excited by a mode locked Ti:sapphire laser beam operating at 800 nm wavelength with the pulse width of 100 fs (FWHM) and maximum energy of 100 mJ per pulse with 10 Hz repetition rate. The neutral density of gas-jet flow is measured with a Mach–Zehnder interferometer. Strength of the applied external dc magnetic field normal to the direction of laser pulse propagation varies from 0 to 8 kG in the interaction region. Radiation is observed, in the forward direction due to the axial component of the magnetized wakefield and in the normal direction due to the radial component of the magnetized wakefield, both perpendicular to the direction of the applied magnetic field. The frequency of the emitted radiation with the pulse width of 200 ps (detection limit), measured by the method of time-of-flight, is in the millimeter wave range. Radiations are polarized perpendicularly to the laser pulse propagation direction and dc magnetic field lines as is expected from the theory. Electrodynamic properties of the radiation have been studied at different plasma densities and magnetic field strengths.