Characterization of two distinct, simultaneous hot electron beams in intense laser-solid interactions

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• High-Energy-Density Physics

Background:

• Energetic electron beams are crucial for various applications, including fast ignition inertial confinement fusion.
• Understanding electron acceleration mechanisms in laser-matter interactions is key to controlling beam properties.

Purpose of the Study:

• To investigate the transport of energetic electron beams generated by ultraintense laser pulses interacting with aluminum foils.
• To identify and differentiate the acceleration mechanisms responsible for the observed electron beams.

Main Methods:

• Imaging coherent transition radiation (CTR) emitted from the rear side of aluminum targets.
• Utilizing ultraintense laser pulses to irradiate the aluminum foils.
• Performing 3D-particle-in-cell (PIC) simulations for theoretical validation.

Main Results:

• Observation of two distinct MeV electron beams simultaneously emitted from the target rear side.
• Evidence suggesting simultaneous operation of resonance absorption and jxB heating mechanisms.
• Demonstration of different electron temperatures and emission directions for the two beams.

Conclusions:

• Resonance absorption and jxB heating are identified as the primary mechanisms accelerating electrons.
• These mechanisms accelerate electrons to different directions and result in distinct electron temperatures.
• The findings are supported by 3D-particle-in-cell simulations, validating the proposed acceleration models.