Abstract
Deuterated polyethylene targets have been irradiated by means of a 1016 W/cm2 laser using 600 J pulse energy, 1315 nm wavelength, 300 ps pulse duration and 70 micron spot diameter. The plasma parameters were measured using on-line diagnostics based on ion collectors, SiC detectors and plastic scintillators, all employed in time-of-flight configuration. In addition, a Thomson parabola spectrometer, an X-ray streak camera, and calibrated neutron dosimeter bubble detectors were employed. Characteristic protons and neutrons at maximum energies of 3.0 MeV and 2.45 MeV, respectively, were detected, confirming that energy spectra of reaction products coming from deuterium-deuterium nuclear fusion occur. In thick advanced targets a fusion rate of the order of 2 × 108 fusions per laser shot was calculated.
Highlights
A high intensity laser interacting with dense matter generates, in vacuum, a non-equilibrium plasma exhibiting high temperature and density and able to drive ion acceleration at energies above 1 MeV per charge state
Regime and/or “advanced” thick targets in Backward PlasmaAcceleration (BPA) regime produces high ion acceleration and hot plasma which enhances the number of fusion events per laser shot, as will be demonstrated by monitoring the characteristic protons and neutrons emitted from the D-D nuclear reaction and as will be discussed below
A typical result obtained during the first experiment, relative to the laser irradiation at 600 J of a thin CD2 foil in Target Normal Sheath Acceleration (TNSA) conditions, is reported in Figure 2 in terms of SiC TOF spectrum for a CD2 foil with a thickness of 5 μm (a) and 50 μm (b) and of charge to ion mass ratios detected through Thomson
Summary
A high intensity laser interacting with dense matter generates, in vacuum, a non-equilibrium plasma exhibiting high temperature and density and able to drive ion acceleration at energies above 1 MeV per charge state. The number of nuclear fusion events is high and it depends on the setting of laser parameters, irradiation conditions and target composition and geometry. These results are due mainly to the kinetic energy of the accelerated deuterons, near the value of the maximum D-D cross-section, more than to the plasma temperature [6]. The use of thin targets in TNSA regime and/or “advanced” thick targets in BPA regime produces high ion acceleration and hot plasma which enhances the number of fusion events per laser shot, as will be demonstrated by monitoring the characteristic protons and neutrons emitted from the D-D nuclear reaction and as will be discussed below
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