Effect of plasma scale length on multi-MeV proton production by intense laser pulses.
The influence of the plasma density scale length on the production of MeV protons from thin foil targets irradiated at I lambda(2) = 5 x 10(19) W cm(-2) has been studied. With an unperturbed foil, protons with energy >20 MeV were formed in an exponential energy spectrum with a temperature of 2.5+/-0.3 MeV. When a plasma with a scale length of 100 microm was preformed on the back of the foil, the maximum proton energy was reduced to <5 MeV and the beam was essentially destroyed. The experimental results are consistent with an electrostatic accelerating mechanism that requires an ultrashort scale length at the back of the target.
Mackinnon
A J
AJ
Lawrence Livermore Laboratory, Livermore, California 94550, USA.
Borghesi
M
M
Hatchett
S
S
Key
M H
MH
Patel
P K
PK
Campbell
H
H
Schiavi
A
A
Snavely
R
R
Wilks
S C
SC
Willi
O
O