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Title: Spectral modification of shock accelerated ions using a hydrodynamically shaped gas target

We report on reproducible shock acceleration from irradiation of a λ=10 μm CO2 laser on optically shaped H2 and He gas targets. A low energy laser prepulse (I≲1014 W cm–2) is used to drive a blast wave inside the gas target, creating a steepened, variable density gradient. This is followed, after 25 ns, by a high intensity laser pulse (I>1016 W cm–2) that produces an electrostatic collisionless shock. Upstream ions are accelerated for a narrow range of prepulse energies. For long density gradients (≳40 μm), broadband beams of He+ and H+ were routinely produced, whilst for shorter gradients (≲20 μm), quasimonoenergetic acceleration of protons is observed. These measurements indicate that the properties of the accelerating shock and the resultant ion energy distribution, in particular the production of narrow energy spread beams, is highly dependent on the plasma density profile. These findings are corroborated by 2D particle-in-cell simulations.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [2] ;  [2] ;  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Imperial College, London (United Kingdom)
  3. Stony Brook Univ., Stony Brook, NY (United States)
Publication Date:
OSTI Identifier:
1226060
Report Number(s):
BNL--108518-2015-JA
Journal ID: ISSN 0031-9007; PRLTAO; R&D Project: KBCH139; KB0202011
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 115; Journal Issue: 9; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS Accelerator Test Facility