研究目的
Investigating the potential of laser-produced plasmas (LPPs) as drivers for creating repeatable collisionless quasi-parallel shocks in the laboratory to study space and astrophysical shocks.
研究成果
The study demonstrates the potential of LPPs as drivers for laboratory quasi-parallel collisionless shocks but highlights the challenge of spatial dispersion. Future experiments and hybrid simulations will explore the use of trains of laser pulses to mitigate LPP dispersion and improve shock driver performance.
研究不足
Spatial dispersion of the laser-produced plasma prematurely terminates the growth of the instability, limiting the maximum wave amplitudes achieved in the current experiments.
1:Experimental Design and Method Selection:
The study combines the Phoenix Laser Laboratory with a large plasma device to explore LPPs as drivers of quasi-parallel shocks. The methodology involves using high-energy lasers to produce plasmas and observing the resulting beam instabilities and waves.
2:Sample Selection and Data Sources:
A pre-magnetized 18 m long, 30 cm diameter cylindrical helium core plasma is produced by two cathodes at either end of the large plasma device (LAPD).
3:List of Experimental Equipment and Materials:
High-energy lasers (Raptor and Peening lasers), plastic (high-density polyethylene, C2H4) targets, and an array of 3-axis, 3 mm diameter magnetic flux probes.
4:Experimental Procedures and Operational Workflow:
A high-energy laser is focused onto a plastic target embedded in the LAPD plasma, and the resulting LPP streams anti-parallel to the background magnetic field. Electromagnetic waves generated by beam instabilities are measured by magnetic flux probes.
5:Data Analysis Methods:
The voltages induced in the probes are differentially amplified, digitized at 1.25 GHz, then numerically integrated to calculate DB. The probes are positioned by motorized probe drives to enable fully autonomous collection of large volumetric datasets.
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