Ultralow emittance, multi-MeV proton beams from a laser virtual-cathode plasma accelerator

Area of Science:

• Plasma Physics
• Particle Acceleration
• Laser-Matter Interactions

Background:

• Conventional accelerators face limitations in producing high-quality, high-current beams.
• Ultraintense lasers offer a novel approach to particle acceleration.
• Understanding beam quality is crucial for applications in various scientific fields.

Purpose of the Study:

• To measure the laminarity of high-current multi-MeV proton beams produced by laser-irradiated metallic foils.
• To compare the emittance of these laser-driven proton beams with those from conventional accelerators.
• To identify factors limiting the beam laminarity.

Main Methods:

• Production of proton beams using ultraintense laser irradiation of thin metallic foils.
• Measurement of transverse and longitudinal emittance for proton energies >10 MeV.
• Characterization of the ion beam source size.

Main Results:

• Proton beams with energies >10 MeV demonstrated exceptional laminarity.
• Transverse emittance <0.004 mm mrad and longitudinal emittance <10(-4) eV s were achieved.
• Beam emittance was found to be 100- to 10,000-fold better than conventional accelerator beams.
• Ion beam source size was measured to be <15 microm (FWHM).

Conclusions:

• Laser-driven proton acceleration produces highly laminar beams with ultra-low emittance.
• Collisions with fast electrons appear to be the primary limitation to beam laminarity.
• These findings highlight the potential of laser-based accelerators for generating high-quality particle beams.