Generating a Triton Beam by Target Normal Sheath Acceleration with a High-Energy Short Pulse Laser for Nuclear Experiments

In a novel experiment, a beam of energetic tritons was generated via the target normal sheath acceleration (TNSA) mechanism using tritiated titanium targets. Commercial 25-mm-thick Ti foil was cut into 500 x 500-mm² squares and exposed for 2 h to ~1 atm. of 99.97% pure tritium gas at 200°C. These targets were irradiated with an on-target intensity of 2 x 10¹⁸ W/cm² with the high-energy (1250-kJ), short-pulse (10-ps) OMEGA EP laser. Using a Thomson parabola velocity analyzer, the energy spectrum of the tritons was found to exponentially decrease with a mean energy of 2.3MeV and a high-energy cutoff at ~10 MeV. Approx. 0.04% of the laser energy transferred to the tritons. The total beam yield was determined to be ~10¹² tritons per pulse, comparable to other TNSA experiments with protons. In a second experiment, the triton beam was directed onto a secondary deuterated-polyethylene target, which produced 10⁸ neutrons from DT fusion nuclear reactions. Further experiments are planned to induce the T(t, 2n)α reaction of interest for ab-initio nuclear structure calculations of ⁶He.