STUD Pulses: Spike Train of Uneven Duration and Delay for the Control of Laser-Plasma Instabilities in ICF, IFE and HEDLP

It is possible to stop the runaway growth of parametric instabilities by breaking up multi-nanosecond laser pulses into a train of spikes on the psec time scale whose amplitudes, durations and inter-spike delays are design parameters adjusted to keep laser plasma instabilities (LPI) from undergoing too many e-foldings (which would be determined experimentally, under given plasma conditions). This new approach also addresses multiple overlapping laser beam (direct drive) and intercone beam crossing (indirect drive) effects which are major concerns for all options for ICF and IFE to date. With STUD pulses, multi-beam interactions are kept under control or disallowed outright by interleaving in time the spikes in different beams. Most importantly, STUD pulses usher in the possibility of the use of green (0.53 $\mu $m) or even 1 $\mu $m radiation as ICF drivers since LPI will now be actively controlled. STUD pulses can be implemented on the NIF by just changing the front end with no need for changes to the amplifier chain. Finally, in the million or more (wide bandwidth) fiber laser approach to IFE in the future, STUD pulses are a natural mechanism to ensure LPI control since the speckle patterns of overlapped randomly timed beams will be naturally independent from spike to spike with very long recurrence times, guaranteeing linear and modest growth in time of instabilities.