Laser-driven dielectric electron accelerator for radiobiology researches
Laser-driven dielectric electron accelerator for radiobiology researches
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DOI：
10.1117/12.2017221
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发表时间：
2013-05
影响因子：
2.4
通讯作者：
K. Koyama;Y. Matsumura;M. Uesaka;M. Yoshida;T. Natsui;Aimidula Aimierding
中科院分区：
文献类型：
--
作者：
K. Koyama;Y. Matsumura;M. Uesaka;M. Yoshida;T. Natsui;Aimidula Aimierding
为了估计与低剂量辐射有关的健康风险，必须了解活细胞中辐射效应的基本过程。期望电子聚束或光子脉冲精确地撞击细胞核和DNA。聚束所需的电子能量和电子电荷分别为几十keV至1 MeV和0.1 fC至1 fC。光束尺寸小于微米有利于精确观测。针对激光驱动介质电子加速器适合于小型化微束源的特点，研究了一种相位调制屏蔽型激光驱动介质电子加速器。虽然初步分析得出的结论是光栅周期和电子速度必须满足LG/λ = v/c的匹配条件，但光栅支柱中波前的变形放宽了匹配条件，并使慢电子得以加速。利用免费的时域有限差分程序Meep模拟结果表明，20 keV的低能电子感受到的加速场强为20 MV/m，随着速度的增加，感受到的场强逐渐增大。最后，超相对论电子感受到600 MV/m的场强。Meep代码还表明，获得1 MeV能量的加速器的长度为3.8 mm，所需的激光功率和能量分别为11 GW和350 mJ。通过采用顺序激光脉冲，对激光的限制得到了缓解。如果用连续N个脉冲照射加速器，则脉冲功率、脉冲宽度和脉冲能量分别减小到1/N、1/N和1/N2。当照射10对连续激光脉冲时，估计每个脉冲所需的激光功率为2.2GW。
In order to estimate the health risk associated with a low dose radiation, the fundamental process of the radiation effects in a living cell must be understood. It is desired that an electron bunch or photon pulse precisely knock a cell nucleus and DNA. The required electron energy and electronic charge of the bunch are several tens keV to 1 MeV and 0.1 fC to 1 fC, respectively. The smaller beam size than micron is better for the precise observation. Since the laser-driven dielectric electron accelerator seems to suite for the compact micro-beam source, a phase-modulation-masked-type laser-driven dielectric accelerator was studied. Although the preliminary analysis made a conclusion that a grating period and an electron speed must satisfy the matching condition of LG/λ = v/c, a deformation of a wavefront in a pillar of the grating relaxed the matching condition and enabled the slow electron to be accelerated. The simulation results by using the free FDTD code, Meep, showed that the low energy electron of 20 keV felt the acceleration field strength of 20 MV/m and gradually felt higher field as the speed was increased. Finally the ultra relativistic electron felt the field strength of 600 MV/m. The Meep code also showed that a length of the accelerator to get energy of 1 MeV was 3.8 mm, the required laser power and energy were 11 GW and 350 mJ, respectively. Restrictions on the laser was eased by adopting sequential laser pulses. If the accelerator is illuminated by sequential N pulses, the pulse power, pulse width and the pulse energy are reduced to 1/N, 1/N and 1/N2, respectively. The required laser power per pulse is estimated to be 2.2 GW when ten pairs of sequential laser pulse is irradiated.