@misc{oai:repo.qst.go.jp:00076035,
 author = {ドーバー, ニコラス ピーター and Dover, NicholasPeter},
 month = {Jun},
 note = {State-of-the-art high power laser facilities present numerous potential applications, including the generation of ultra-short and low emittance ion beams. Understanding the underlying laser-plasma interaction physics and resulting scaling to ultra-high intensities is of great importance for optimising such sources. We therefore present experimental data of proton acceleration in a sheath field using the ultra-high intensity J-KAREN-P laser (10 J, 40 fs, 5x1021 W/cm2), allowing investigation at the high-intensity frontier.
A repetitive tape target was used to generate proton beams at a 0.1 Hz repetition rate limited only by the laser, allowing a systematic and comprehensive scan over laser parameters. Our laser-target system is able to regularly produce protons in excess of 40 MeV at the full repetition rate. We will demonstrate a slower than expected increase in proton energy with decreasing focal spot size, show that this is due to a reduced sheath lifetime for tight focal spots, and propose a new model which successfully predicts proton energies over a large range of focal spot sizes., OPTO2019},
 title = {Effect of small focus on electron heating and proton acceleration in ultra-relativistic laser-solid interactions},
 year = {2019}
}