Ion Heating and Thermonuclear Neutron Production from High-Intensity Subpicosecond Laser Pulses Interacting with Underdense Plasmas

Thermonuclear fusion neutrons produced by D(d,n)³He reactions have been measured from the interaction of a high-intensity laser with underdense deuterium plasmas. For an input laser energy of 62 J, more than (1.0±0.2)×10⁶ neutrons with a mean kinetic energy of (2.5±0.2) MeV were detected. These neutrons were observed to have an isotropic angular emission profile. By comparing these measurements with those using a secondary solid CD₂ target it was determined that neutrons are produced from direct ion heating during this interaction.