Observation of strongly collimated proton beam from Tantalum targets irradiated with circular polarized laser pulses

Abstract

High-energy protons are generated by focusing an ultrashort pulsed high intensity laser at the Advanced Photon Research Center, JAERI-Kansai onto thin~thickness ,10 mm! Tantalum targets. The laser intensities are about 4 ϫ 10 18 W0cm 2 . The prepulse level of the laser pulse is measured with combination of a PIN photo diode and a cross correlator and is less than 10 Ϫ6 . A quarter-wave plate is installed into the laser beam line to create circularly polarized pulses. Collimated high energy protons are observed with CH coated Tantalum targets irradiated with the circularly polarized laser pulses. The beam divergence of the generated proton beam is measured with a CR-39 track detector and is about 6 mrad.

New Method to Measure the Rise Time of a Fast Pulse Slicer for Laser Ion Acceleration Research

“…Without the pulse slicer, the ASE pedestal was long (τ pre ∼ 4 ns), and we observed only low-energy protons (100-350 keV) using thin foil target of a few micrometers [28]. For ASE pedestal control, long focal length optics were used for suppressing the ASE pedestal effect by suppressing its intensity.…”

The role of hollow atoms in the spectra of an ultrashort-pulse-laser-driven Ar cluster target

“…The Ar cluster experiments were performed with the Japan Atomic Energy Agency (JAEA) (Kyoto, Japan) Ti:sapphire laser system based on the technique of chirped pulse amplification, which was designed to generate 20 fs pulses and is capable of producing a focused intensity up to 10 20 W/cm 2 (Yamakawa et al, 1998;Kado et al, 2006;Akahane et al, 2006). In this study the amplified pulses were compressed to 30 fs by a vacuum pulse compressor yielding a maximum pulse energy of 360 mJ Abdallah et al, 2003;Sherrill et al, 2006).…”

“…Other important experimental studies of hollow ion formation have also been carried out at GSI . Laser-plasma interactions probing production of multicharged accelerated ions or warm dense matter have also been studied extensively (see for example, Cao et al, 2007;Batani et al, 2007;Nickles et al, 2007;Faenov et al, 2007;Kado et al, 2006). Experiments at JAEA have probed Ar clusters for hollow atom production, and other studies have been done on laser absorption mechanisms in clusters (Kanapathipillai, 2006).…”

Quasi-monoenergetic proton beam generation from a double-layer solid target using an intense circularly polarized laser

“…Using circularly polarized (CP) laser pulses, a new mechanism radiation pressure acceleration (RPA) was considered for monoenergetic ion beam generation (Macchi et al, 2005;Kado et al, 2006;Liseikina & Macchi, 2007;Zhang et al, 2007;Klimo et al, 2008;Robinson et al, 2008;Yan et al, 2008). Without high-frequency oscillating component of the v  B force for a CP laser pulse, there is no heating originating from the hot electron oscillations when it is normally incident on a target (Macchi et al, 2005).…”