Photon Acceleration and Its Mechanisms Induced in Plasma by Intense Microwave

本项目的任务是阐明电磁波在辐照等离子体的频率上产生蓝移或光子加速的机制。这一现象最初是我们实验室在用强微波代替高功率短脉冲激光照射等离子体模拟激光尾场加速过程中观察到的。在本工作中，我们具体观察到了两种现象，一种是强微波引起的电离，另一种是在没有或几乎没有电离的情况下观察到的现象。在第二种情况下，腔内存在的强驻波通过有重量的动力推动等离子体移动，从而产生蓝移。这两种情况的关键区别在于，在没有电离的情况下，可以清楚地观察到频率在6-20 MHz的上边带子波。如果伴随电离，这些子频分量不明显，观察到较宽的带谱。作为Ptesent现象的一个应用，我们展示了DC-AC辐射转换(DARC)现象的可能性。这是超短脉冲微波从静电场中直接辐射的过程。

The task of this project is to clarify the mechanism of the blue-shift or photon acceleration induced in the frequency of electromagnetic wave irradiated to the plasma. This phenomenon was observed originally in our Laboratory in the investigations related to the laser wakefield acceleration which is simulated by the intense microwavw irradiation to the plasma instead of high power, short pulse laser.In the present works, we have observed specifically two kinds of phenomena, the one is followed by ionization induced by a strong microwave and the other is the phenomena observed in the situation where there is no or almost no ionization. In the second case, the strong standing wave existing within the chamber push to move the plasma by a ponderomotive force to create a blue-shift. The Key differences between two cases are that the upper side-band daughter waves with frequencies such as 6-20 MHz have seen clearly observed when there is no ionization. If the ionization are accompanied, these daughter frequency components are not clear, rather broad band spectrums are observed. As an application of the ptesent phenomena, we have shown the possibilities of DC-AC Radiation Conversion (DARC) phenomenon. This is a direct radiation process of ultra-short pulse microwaves from electrostatic fields.