Allen, M.

Cobble, J. A. (James A.)

Cowan, T. E.

Fernández, J. C. (Juan C.)

Gibson, R. B. (Robert B.)

Johnson, R. P. (Randall P.)

Renard-Le Galloudec, N

UNT Digital Library

LA-UR- 62 qLl L\ Approved for public release; distribution is unlimited. c 9' Title: Author&). Submitted to LASER-PRODUCED MEV PROTONS ON TRIDENT J. A. Cobble J. C. Fernandez R. B. Gibson R. P. Johnson T. Cowan N. Le Galloudec M. Allen 32nd Anomalous Absorption Conference Turtle Ray, Oahu, Hawaii July 21 -26, 2002 1 -4% 0 LosAlamos N A T I O N  AI.. L A B 0  R A T 0  R Y  Los Alamos National Laboratory, an affirmative action/equal opportunity employer, is operated by the University of California for the US. Department of Energy under contract W-7405-ENG-36. By acceptance of this article, the publisher recognizes that the US. Government retains a nonexciusive, royalty-free license to publish or reproduce the published form of this contribution, or to allow others to do so, for US. Government purposes. Los Aiamos National Laboratory requests that the publisher identify this article as work performed under the auspices of the US. Department of Energy. Los Alamos National Laboratory strongly supports academic freedom and a researcher's right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness. Form 836 (8/00) Laser-Produced MeV Protons on Trident J. A. Cobble, J. C. Fernhdez, R. B. Gibson, R. P. Johnson, Los Alamos National Laboratory T. Cowan, General Atomics N. Renard-Le Galloudec, University of Nevada, Reno M. Allen, University of California, Berkeley 32nd Anomalous Absorption Conference Turtle Bay, Oahu, Hawaii July 21-25, 2002 - I I PS green beam strikes a thin metal target driving off electrons U I I n I A large electric field I electrons leave, pulling ions from the surface. U 1 Protons in a narrow half I n angle cone are accelerated up to several MeV by the field rident Short Pulse System pulse generator amplifier 45-mm rod 26-mm rod 16-mm rod amplifier amplifier amplifier t i j j I i i i ! j 1 i i i j j j i 14-cm disk more 10-cm amplifier amplifier b gratings doubler and rattle plate aser Performance Pulse duration - 600 fs Green energy >1 J Power 1.5 0.3 TW Focal Spot - 2.4 pm x 2.7 pm for l/e2 diameter with f/2 off-axis parabola Target irradiance - 3 x 1019 W/cm2 Pre-lase contrast 350 ps prior to the main pulse -lolo Number of target shots - 55 Targets: Au, 0.5 - 25 pm thick Al, 3 - 25 pm 4 0 LosAlamos N A T I O N A L  L A B O R A T O R Y  Autocorrelator Pulse Width. 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (ps) This typical autocorrelator trace shows a FWHM -0.78 ps and corresponds to a pulse width of -550 fs. Main-pulse to prelase contrast in the green is measured to be lo1' at 350 ps prior to the main pulse. This is made possible by four Pockel cells, including two on the input to the regenerative amplifier, and a rattle plate for removing 1054-nm light. The 1-a contrast at the same time is -lo7. Laser Spot Size 48x 38x 29x 194 1BX -Bx Diameters, 1/e2 = 2.70, 2.45 pm Proton Diagnostics Faraday cup time-of-flight detector CR39 nuclear particle track detectors Faraday Cup Data - to scope I -30 VDC 0 10 Time (ns) 20 Photoelectron current from x rays mark t = 0. The proton current beginning at 5 ns implies -600 keV protons. but the signal is lower by -4OX. For Au targets, the bulk cutoff energy is higher At the foot of the Faraday cup trace is a faster component! Digital oscilloscope data show a population of fast protons leading the slower bulk distribution. The high-energy cutoff for this superthermal tail is nearly 6 MeV. 0.3  I y = 0 . 0 6 7 ~  - 0.101 r2 = 0.873 n 0.2 0.1 0 I M , ,  I 1 ' 1 , 1 1 1  I . ,  , 1 1 1 1  I , , ,  , I ,  I , ,  , , ,  , " L  I I I I 2 3 4 Time (ns) 5 a' Los Alamos N A T I O N A L  L A B O R A T O R Y  Yield Correc ed for Secondary Electrons 20 5 0 5 0 raw protonsMeV ... I...... . m - - - - -  0.0 0.5 I .o 1.5 2.0 Energy (MeV) 1) M. Rosler, Nucl. Instrum. Methods Phys. Res. B 115, 278,1996. 2) E. Steinbauer, A. Schinner, and 0. Benka, Nucl. Instrum. Methods Phys. Res. B 171,291 2000. Integrating under the blue curve, we find -5 x lo9 protons in the energy range 0.2 - 2 striking the cathode. This is a lower bound. e back surface of ;a double layer ndicatc proton energy of 18 MeV or rnorc. lamas IN A I I O  1 i\ I I A 1; 0 I I  1% I 0 i i  Y I I 0 5 i o  15 20 2s  A ar, :c a cmds to tlec:rease as target thickness i.nciw a, s c s 

Laser-produced MeV protons on trident

https://digital.library.unt.edu/ark:/67531/metadc926287/m2/1/high_res_d/976229.pdf

Laser-produced MeV protons on trident

Abstract

Similar works

Full text

Available Versions

UNT Digital Library