Longer Wavelength Lasers for Inertial Fusion Energy with Laser-Plasma Instability Control: Machine Learning Optimum Spike Trains of Uneven Duration and Delay (STUD Pulses)

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OPEN 2021
Pleasanton, California
Project Term:
09/20/2022 - 03/19/2025

Critical Need:

To date, inertial fusion energy (IFE) has focused on the third harmonic of glass lasers because laser-plasma instabilities (LPI), which degrade the compression of fusion fuel, are reduced at their short wavelengths. However, the nonlinear optical processes that shift laser light from a fundamental wavelength to second and third harmonics are inefficient. The use of longer wavelength lasers in inertial confinement fusion, such as the second harmonic of glass lasers, enables larger drive energy, cheaper cost, larger bandwidth (not usurped by third-harmonic generation), and higher glass-damage thresholds. On the other hand, longer wavelengths, if unmitigated, enhance the risk of LPI.

Project Innovation + Advantages:

Polymath Research will enable the use of longer-wavelength lasers for IFE. This project seeks to control LPI using pulses composed of Spike Trains of Uneven duration and Delay (STUD), a sequence of precisely timed laser pulses designed to disrupt LPI growth and memory build up in the plasma due to persistent self-organization of the plasma undergoing continuous and undisrupted laser energy deposition. The challenge is that with rather limited knowledge of the dynamic (micro-) state of the plasma, laser pulses composed of STUD must be devised to combat memory build up and exponential reamplification. The team will use data from simulation models and high-repetition-rate lasers to train a multitude of machine-learning algorithms to select optimal spike trains and define conditions where longer-wavelength, laser-triggered LPI can be successfully tamed. These predictions will then be tested in follow-on work on a laser facility operating at high energy.

Potential Impact:

Controlling LPI on the scale of instability growth times is a game changer for all laser-based IFE schemes.


The STUD-pulse program for LPI technology enhances the technical prospects of IFE for potentially abundant fusion power generation.


IFE is a promising non-carbon-emitting source of dispatchable primary energy.


The design and licensing of custom-made STUD pulses for LPI control for myriad IFE schemes using principled machine learning lends itself to potentially economical commercial fusion energy.


ARPA-E Program Director:
Dr. Ahmed Diallo
Project Contact:
Dr. Bedros Afeyan
Press and General Inquiries Email:
Project Contact Email:


Colorado State University

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