超热电子的产生与输运背向辐射的测量
Measurement of Hot Electrons Generation and Transport in Targets at Rearside Radiation
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摘要: 报道了在20TWfs激光器上采用电子磁谱仪和光学CCD积分成像相机分别对激光固体靶相互作用在靶背方向产生的超热电子能谱及其光学渡越辐射进行的测量。能谱测量结果显示:超热电子能谱呈双温类麦克斯韦分布,拟合的温度分别为90和280keV,平均温度为185keV,这与已知的温度定标率较好地吻合。光学渡越辐射测量结果显示:光学渡越辐射是由于超热电子输运穿越固体靶所致,而辐射区域呈圆盘状、有发散角、有光强分布。如果考虑超热电子的产生和加热机制,则占主导地位的加热机制是共振吸收对电子的加热。Abstract: This paper reports hot electron energy spectrum measured with electron spectrometer, and Optical Transition Radiation measured with optical timeintegrated image of CCD during the interaction of lasersolid target in targets at the rearside radiation of laser on 20 Terawatt femtosecond laser facility. It shows that hot electron energy spectrum can be fitted with twotemperature likeMaxwellian distribution, with T≈90 and 280 keV,but average temperature of hot electrons T≈185 keV, which accorded with the known temperature scaling law. Because Optical Transition Radiation is produced by the hot electrons transport through solid targets, region of Optical Transition Radiation has lager radiation angle and optical intensity distribution. The main acceleration of hot electron comes from resonance absorption.
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