Development of THz-range Gyrotrons for Detection of Concealed Radioactive Materials
Development of THz-range Gyrotrons for Detection of Concealed Radioactive Materials
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开发用于探测隐藏放射性物质的太赫兹范围回旋管
DOI：
10.1007/s10762-010-9708-y
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
V. Granatstein
中科院分区：
文献类型：
--
作者：
G. Nusinovich;R. Pu;T. Antonsen;O. Sinitsyn;J. Rodgers;A. Mohamed;J. Silverman;M. Al;Y. Dimant;G. Milikh;M. Glyavin;A. Luchinin;E. A. Kopelovich;V. Granatstein
马里兰州大学应用电磁学中心已开始研制用于探测隐藏的放射性材料的亚太赫兹回旋管。这个概念是基于使用一个高功率回旋管，其功率被集中在一个小斑点的尺寸上的顺序的波长超过阈值水平所需的启动自由本地化的微波击穿在空气中。然而，在没有放射性物质的情况下，周围的电子密度是如此之小，以至于在这个小体积中找到一个自由电子来触发雪崩击穿过程的概率非常小。因此，观察到击穿这一事实将表明，在聚焦波束附近隐藏着放射性物质。本文给出了一个200-300 kW，670 GHz脉冲螺线管回旋管的设计数据，并描述了一个产生27-28 T磁场的单脉冲螺线管。还讨论了这一具体应用中的许多问题，即引发击穿的阈值条件，隐藏的放射性物质产生γ射线及其在容器外产生低能电子中的作用，有限尺寸天线将波束聚焦在小光斑中，高能电子的随机游走，这可能导致在RF脉冲期间在给定体积中出现自由电子，并将扩散时间与时间进行比较竞争过程所需的，如电离和三体附着。
The Center for Applied Electromagnetics (AppEl) at the University of Maryland had started development of a sub-THz gyrotron for detecting concealed radioactive materials. The concept is based on the use of a high-power gyrotron whose power being focused in a small spot with dimensions on the order of a wavelength exceeds the threshold level required for initiating a freely localized microwave breakdown in air. However, in the absence of radioactive materials, the ambient electron density is so small that there is a very small probability to find a free electron in this small volume to trigger the avalanche breakdown process. Therefore the fact that the breakdown was observed would indicate that there is a hidden radioactive material in the vicinity of a focused wave beam. We present the design data for a 200–300 kW, 670 GHz gyrotron operating with a pulsed solenoid and describe a single-shot pulsed solenoid producing 27–28 T magnetic fields. Also numerous issues in this specific application are discussed, viz. threshold conditions for initiating the breakdown, production of gamma rays by concealed radioactive materials and their role in producing low energy electrons outside a container, wave beam focusing in a small spot by a limited-size antenna, random walk of energetic electrons which may result in appearance of free electrons in a given volume during the RF pulse and comparison of diffusion time with the time required for competing processes, such as ionization and three-body attachment.
影响因子：
19.6
作者：
Sakamoto, Keishi;Kasugai, Atsushi;Kajiwara, Ken
通讯作者：
Kajiwara, Ken