Berlin 2014 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 24: Laser Plasmas I
P 24.4: Vortrag
Donnerstag, 20. März 2014, 14:45–15:00, SPA HS202
Improvement of laser absorption by tailoring of the ASE pedestal in target normal sheath acceleration with mass limited targets — •Jens Polz1, Alex Robinson3, Alex Arefiev4, Ajay Arunachalam1,2, Georg Becker1, Maria Reuter1,2, Matthew Schwab1, Alexander Sävert1, and Malte Kaluza1,2 — 1Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, D-07743 Jena — 2Helmholtz Institut, D-07743 Jena — 3Central Laser Facility, Rutherford-Appleton Laboratory, Chilton, Oxon., OX11 0QX, UK — 4Institute for Fusion Studies, The University of Texas, Austin,Texas 78712, USA
For ion acceleration from thin foils using high-intensity laser pulses in the TNSA regime, reducing the laser pulse contrast Iprepulse/Imain pulse allows using thinner foils, which leads to higher ion energies. What is neglected in this consideration is that for the absorption of laser light by the plasma, the properties of the generated pre-plasma plays a crucial role. Here we show experimental results, where we controlled the length of the ASE pedestal with a laser pulse contrast level of 10−8 in an experiment where water micro droplets were used as targets. When increasing the length of the ASE pedestal the energy of the accelerated protons increased. Theoretical investigations show that for the shortest possible ASE pedestal length, the absorption of the laser is dominated by transverse ponderomotive acceleration (TPA), whereas when increasing the ASE pedestal length it is dominated by leading edge depletion (LED). In the LED regime the energy of the generated electrons is enhanced, thus leading to an increase in proton energies.