| Autor: |
Reed, S. A., Bulanov, S. S., Chvykov, V., Brantov, A., Bychenkov, V. Yu., Kalinchenko, G., Matsuoka, T., Rousseau, P., Yanovsky, V., Litzenberg, D. W., Maksimchuk, A. |
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| Zdroj: |
AIP Conference Proceedings; 2006, Vol. 877 Issue 1, p430-436, 7p, 3 Graphs |
| Abstrakt: |
The acceleration of protons to therapeutic energies of over 200 MeV by short-pulse, high-intensity lasers requires very high temporal intensity contrast. We describe improvements to the contrast ratio of the laser pulse produced by a multi-terawatt chirped pulsed amplification (CPA) Ti:sapphire laser for the application of proton acceleration. The modified cross-polarized wave generation (XPW) technique has been implemented on the Hercules laser at the University of Michigan to reject the low-intensity amplified spontaneous emission (ASE) preceding the main laser pulse. We demonstrate that by using two BaF2 crystals, the XPW technique yields a 10-11 contrast ratio between the main peak and the ASE for a 50 TW laser system which can be maintained up to 500 TW. Such contrast may be sufficient for a preplasma-free interaction of 225 TW laser pulses with sub-micron thick foils at an intensity of ∼1022 W/cm2. Particle-in-cell (PIC) simulations were conducted under the anticipated experimental conditions: 6.75 J, 30 fs laser pulse without a prepulse, focused to a spot size of 1.2 microns (FWHM) on thin foils of varying thickness. The performed PIC simulations show that for a 0.2 μm thick hydrogen foil protons with energy up to 200 MeV can be produced. In the case of the two-layer aluminum-hydrogen foil, the maximum energy of accelerated protons is about 150 MeV, but the flux-energy spectrum of the accelerated protons has a narrow peak at high energies, which may be more advantageous for medical applications. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR] |
| Databáze: |
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