Enhanced ion acceleration from transparency-driven foils demonstrated at two ultraintense laser facilities

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• Particle Acceleration

Background:

• Laser-driven ion sources offer high energy, high peak current beams for applications like compact medical accelerators.
• Robust acceleration schemes require stability and controllability, which are sensitive to laser temporal contrast.

Purpose of the Study:

• To demonstrate robust generation of energetic ions using ultraintense femtosecond lasers and thin Formvar foils.
• To investigate the influence of laser contrast on ion acceleration performance and target requirements.
• To identify interaction parameters for application-specific energetic ion beam delivery.

Main Methods:

• Irradiation of sub-micrometre Formvar foils with ultraintense lasers (>10^21 Wcm^-2).
• Generation of extreme localized space charge fields (≳30 TVm^-1) via relativistically induced transparency.
• Replication of the acceleration mechanism on two different laser facilities.

Main Results:

• >60 MeV protons and >30 MeV u^-1 carbon ions were generated.
• Optimum target thickness decreased with improved laser contrast due to reduced pre-expansion.
• Ion acceleration was demonstrated across different laser contrast levels.

Conclusions:

• Energetic ions can be accelerated via relativistically induced transparency, even with varying laser contrast.
• This mechanism relaxes stringent laser requirements, broadening applicability.
• The study provides insights into optimizing parameters for application-specific ion beam generation.