Dover N P, Nishiuchi M, Sakaki H, Kondo Ko, Alkhimova M A, Faenov A Ya, Hata M, Iwata N, Kiriyama H, Koga J K, Miyahara T, Pikuz T A, Pirozhkov A S, Sagisaka A, Sentoku Y, Watanabe Y, Kando M, Kondo K
Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, Kizugawa, Kyoto 619-0215, Japan.
PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
Phys Rev Lett. 2020 Feb 28;124(8):084802. doi: 10.1103/PhysRevLett.124.084802.
Acceleration of particles from the interaction of ultraintense laser pulses up to 5×10^{21} W cm^{-2} with thin foils is investigated experimentally. The electron beam parameters varied with decreasing spot size, not just laser intensity, resulting in reduced temperatures and divergence. In particular, the temperature saturated due to insufficient acceleration length in the tightly focused spot. These dependencies affected the sheath-accelerated protons, which showed poorer spot-size scaling than widely used scaling laws. It is therefore shown that maximizing laser intensity by using very small foci has reducing returns for some applications.
研究了高达5×10²¹W/cm²的超强激光脉冲与薄箔相互作用产生的粒子加速情况。电子束参数不仅随激光强度变化，还随光斑尺寸减小而变化，导致温度降低和发散减小。特别是，在紧密聚焦光斑中，由于加速长度不足，温度达到饱和。这些相关性影响了鞘层加速质子，其光斑尺寸缩放比广泛使用的缩放定律要差。因此表明，对于某些应用来说，通过使用非常小的焦点来最大化激光强度的收益会逐渐减少。
