Short intense laser pulse collapse in near-critical plasma

Area of Science:

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

Background:

• Intense ultrashort laser pulses interacting with matter can lead to complex phenomena.
• Understanding energy deposition and particle acceleration is crucial for applications like inertial confinement fusion and advanced accelerators.

Purpose of the Study:

• To investigate the interaction of intense ultrashort laser pulses with near-critical gas jets.
• To characterize the resulting plasma expansion and electron dynamics.
• To elucidate the mechanisms behind energy deposition and particle acceleration.

Main Methods:

• Optical monitoring of plasma expansion in time and space.
• Analysis of electron acceleration and heating.
• Numerical simulations of laser-plasma interaction.

Main Results:

• Observed pulse collapse and significant energy deposition in a localized region.
• Efficient acceleration and heating of electrons in the rising part of the gas jet.
• Collisionless plasma expansion at subrelativistic velocities (~ c/3) over ~ 150 μm.
• Attribution of expansion to quasistatic field ionization driven by hot electron currents.
• Numerical simulations confirmed relativistic electron acceleration and excitation of a magnetic dipole sustaining electron currents for picoseconds.

Conclusions:

• The interaction leads to efficient energy transfer from the laser pulse to electrons.
• The observed plasma expansion is driven by self-generated fields and hot electron currents.
• Relativistic electron acceleration and magnetic field generation are key features of this process.