GHz Frame-Rate Laser Diagnostics of HED Plasmas for 10 Hz LaserNetUS Facilities

Studies of laser-driven high energy density plasma physics require large, complex laser systems providing well-controlled pulses at extreme intensities reaching petawatt levels. New facilities, several of which exist within the LaserNetUS consortium, have increased the operation rate such laser sources to the 10 Hz regime, allowing thousands of high energy experiments to be performed within minutes. The ability to collect large data sets will enable more thorough and robust data analysis, particularly by leveraging machine learning and artificial intelligence techniques. However, high fidelity plasma diagnostics are required at commensurate repetition rates, fully capturing the laser-plasma dynamics of each individual shot, to realize the full research potential of these facilities. While several plasma diagnostic techniques with high temporal resolution exist at 10 Hz, these methods are unable to temporally characterize a single high energy laser plasma event. Since these dynamics take place on timescales ranging from pico- to nanoseconds, imaging techniques with GHz frame rates are required to properly track their evolution; frame gating on the single picosecond level is also necessary to freeze plasma movement withing a single frame. The proposed imaging technique maintains picosecondlevel temporal resolution while simultaneously capturing 2D plasma dynamics at up to 10 GHz. Furthermore, while the current proposal supports 10 Hz delivery of GHz imaging bursts, this delivery rate is only limited by the operation of the petawatt lasers within the LaserNetUS network. Scaling delivery to much higher repetition rates is possible through straightforward modifications of the laser probe source. A system delivering ultrafast pulse bursts at GHz repetition rates was developed and implemented to image laser plasma formation, plasma expansion, and shockwave generation with picosecond resolution. The GHz bursts generated by the laser probe were conditioned such that each pulse within the probe had a distinct temporal delay and spectral content. This allowed a single camera detector image each pulse independently using a spectrally selective imaging system. Achieving single shot GHz imaging with a single camera, while using affordable components and maintaining a compact footprint, is a significant achievement that will provide LaserNetUS research facilities with advanced measurement capabilities that do not currently exist. The GHz laser probe and imaging system will be consolidated into a compact, turn-key commercial system that is readily transportable and provides simple operation by user facilities. This system will be validated at a high energy research lab before being deployed at LaserNetUS facilities. Successful demonstration at LaserNetUS facilities will greatly benefit the Department of Energy and lead to strong commercialization potential. Aside from the direct benefit to the Department of Energy related to GHz rate imaging of high energy density laser plasmas, this technology offers several robust commercialization pathways. There is significant potential for market adoption within the cold ablation and precision laser processing industry, particularly the multi-billion-dollar optical display market that calls for low-heat laser cutting, etching, and marking. Precision laser machining is enabled by products identical to the laser proposed here: ultrafast pulse durations (precision, athermal material modification) at high-repetition rates (GHz) with tunable burst formats (advanced thermal mitigation). The technology used to develop the single camera detection portion of this diagnostic will also be marketed within the compressive imaging sector. This includes applications defense, astronomy, agriculture, molecular biology, biomedical imaging, geosciences, chemical analysis, and food inspection that constitute multibillion-dollar industries. In addition to the commercial potential within the industrial sector, the source developed here will likely receive research funding and commercial sales from academic and government laboratories as a diagnostic research tool, particularly relative to hypersonic imaging and measurements of rotating detonation engines.