Laser Acceleration of Ultrashort Ion Bunches and Femtosecond Neutron Sources

We have theoretically investigated the acceleration of ions in the interaction of high intensity, circularly polarized laser pulses with overdense plasmas. By using 1D and 2D particle-incell (PIC) simulations we find that high-density, short duration ion bunches moving into the plasma are promptly g...

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Bibliographic Details
Main Authors: Macchi, A, Cattani, F, Liseykina, T V, Cornolti, F
Format: Conference Proceeding
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ACCELERATION
BEAM BUNCHING
DEUTERIUM
ELECTRONS
ION BEAMS
ION DENSITY
IONS
KEV RANGE
LASERS
MEV RANGE
NEUTRON SOURCES
NEUTRONS
PARTICLE BEAMS
PLASMA
PLASMA DENSITY
PLASMA HEATING
PLASMA SIMULATION
POLARIZATION
PULSES
SCALING LAWS
TRITIUM TARGET
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Summary:We have theoretically investigated the acceleration of ions in the interaction of high intensity, circularly polarized laser pulses with overdense plasmas. By using 1D and 2D particle-incell (PIC) simulations we find that high-density, short duration ion bunches moving into the plasma are promptly generated at the laser-plasma interaction surface. This regime is qualitatively different from ion acceleration regimes driven by fast electrons, such as sheath acceleration at the back of the target or shock acceleration at the front, which occur for linear polarization. A simple analytical model accounts for the numerical observations and provides scaling laws for the ion bunch velocity and generation time as a function of pulse intensity and plasma density. The present mechanism based on circular polarization of the laser pulse leads to moderate ion energies (in the 100 keV-1 MeV range) but very high ion densities and low beam divergence. These ion bunches might be of interest for problems of compression and acceleration of high - density matter by short pulses as well as for the development of compact neutron sources. We analyzed a scheme based on two-side irradiation of a thin foil deuterated target, where two colliding ion bunches are produced leading to an ultrashort neutron burst. We evaluated that, for intensities of a few 1019 W cm-2, more than 103 neutrons per Joule may be produced within a time shorter than one femtosecond. Another scheme based on a layered deuterium-tritium target is outlined.
ISSN:0094-243X
1551-7616
DOI:10.1063/1.2195213