一种X射线聚焦光学及其在X射线通信中的应用∗

摘要

X-ray communication, which was first introduced by Keith Gendreau in 2007, is potential to compete with conven-tional communication methods, such as microware and laser communication, against space surroundings. Researchers have spent much time and effort on the mission making the initial idea into reality in recent years. Eventually, the X-ray communication demonstration system based on the grid-controlled X-ray source and single-photon detection technique can deliver both audio and video information in a 6-meter vacuum tunnel, and the bit-error-rate performance of the communication system is analyzed. But it is difficult to implement applications in industries. The point is to find a way to reduce the signal divergence geometrical attenuation and increase the distance of the communication which can be regarded as an important foundation of future deep-space X-ray communication applications. Therefore, it is urgent to study the X-ray communication system. By using a nested X-ray focusing optics as transmitting and receiving anten-nas of the communication system, the signal gain and the distance of X-ray communication can be greatly improved. Specifically, the nested X-ray focusing optics is similar to the Wolter type I telescope, which is widely used in the field of X-ray astronomy. The difference between them is that the Wolter type I optics is originally proposed based on a paraboloid mirror and a hyperboloid mirror, but X-ray focusing optics, the simplified Wolter type I optics, provides a single reflection by a conical approximation mirror, and it is more suitable for X-ray communication. In this paper, aiming at the future demand of X-ray communication, the optimization and analysis of the nested X-ray focusing optics are carried out, and the recurrence relations between the layers of mirrors are derived. Reasonable initial structural parameters and structure of the optics are designed. In addition, the theoretical effective collection area is calculated. Feasibility of using the X-ray focusing optics as transmitting and receiving antennas is analyzed, and the theory and structural design of the X-ray focusing optical are discussed. Signal divergence of transmitting antenna, effective area of receiving antenna, the focal spot size, and the signal gain properties are preliminary studied. The results show that the signal divergence is about 3 mrad, and the transmit gain is 23 dB;the effective area of receiving antenna is 5700 mm2 at 1.5 keV. Moreover, the focal spot diameter and the receive gain are 4.5 mm and 25 dB, respectively, and the total gain of this communication system can reach up to 48 dB.%基于栅控脉冲发射X 射线源与单光子探测技术的X 射线通信已经实现了实验室语音通信验证,并对通信系统的误码率性能进行了分析,为探索未来X 射线深空应用打下了坚实的基础.针对目前X 射线通信面临的信号发散角大、通信距离短、难以实现工程化应用的情况,迫切需要对X 射线通信天线系统进行深入研究.为了提高信号增益、增大X 射线通信的距离,提出了多层嵌套式X 射线聚焦光学作为X 射线通信的“收发天线”,理论分析了X 射线聚焦光学用于X 射线通信“收发天线”的可行性,分析了X 射线聚焦光学的理论基础与结构设计,对“发射天线”发散角、“接收天线”有效面积与焦斑尺寸、信号增益等性能做了探讨.结果表明：在信号发射端,“天线”的发散角为3 mrad 左右,发射增益23 dB；在信号接收端,“接收天线”的有效面积5700 mm2@1.5 keV,焦斑直径为4.5 mm,接收增益为25 dB,通信系统总的增益可达48 dB.