Laser-Driven Proton-Only Acceleration in a Multicomponent Near-Critical-Density Plasma.

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• Astrophysical Phenomena

Background:

• Collisionless shocks are fundamental in space and astrophysical plasmas.
• Understanding ion acceleration mechanisms in these shocks is crucial.
• Previous studies often involved simpler plasma compositions.

Purpose of the Study:

• To experimentally investigate ion acceleration in collisionless shocks.
• To explore selective ion acceleration using multicomponent plasmas and intense lasers.
• To provide insights into the physics of inaccessible astrophysical shocks.

Main Methods:

• Utilizing a multicomponent plasma target.
• Employing a high-intensity, picosecond-duration laser pulse.
• Conducting particle-in-cell (PIC) simulations for theoretical support.

Main Results:

• Protons were observed as the sole accelerated ions under specific laser and plasma conditions.
• Near-critical-density plasma driven by a laser with modest normalized vector potential favored proton acceleration.
• PIC simulations corroborated the selective acceleration of protons by collisionless shocks.

Conclusions:

• Collisionless shocks can selectively accelerate protons in multicomponent plasmas.
• This selective acceleration offers a novel approach to studying shock physics.
• The findings have implications for understanding and modeling space and astrophysical plasma environments.