Maksimchuk A, Gu S, Flippo K, Umstadter D, Bychenkov VY
Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA.
Phys Rev Lett. 2000 May 1;84(18):4108-11. doi: 10.1103/PhysRevLett.84.4108.
A collimated beam of fast protons, with energies as high as 1.5 MeV and total number of greater, similar10(9), confined in a cone angle of 40 degrees +/-10 degrees is observed when a high-intensity high-contrast subpicosecond laser pulse is focused onto a thin foil target. The protons, which appear to originate from impurities on the front side of the target, are accelerated over a region extending into the target and exit out the back side in a direction normal to the target surface. Acceleration field gradients approximately 10 GeV/cm are inferred. The maximum proton energy can be explained by the charge-separation electrostatic-field acceleration due to "vacuum heating."
当一个高强度高对比度亚皮秒激光脉冲聚焦到薄箔靶上时，会观察到一束准直的快质子束，其能量高达1.5兆电子伏特，总数更多，类似10⁹，被限制在40度±10度的锥角内。这些质子似乎起源于靶前侧的杂质，在延伸到靶内的区域被加速，并沿垂直于靶表面的方向从靶后侧射出。推断出加速场梯度约为10吉电子伏特/厘米。最大质子能量可以用“真空加热”导致的电荷分离静电场加速来解释。
