The physics of penetrating the relativistic electron beam (REB) into stationary background plasma is very important in various laboratories and applications, especially in ion channel production or in stable transmission of REB. The production of ion channel via various ways for many applications, such as development of the pulsed power laser, has become a topic of interesting researchers in the past years.
[1-2] There are different devices to produce ion channel which, one of these devices is injecting the relativistic electron beam into plasma environment. This relativistic electron beam can be cold or warm, which both methods have been used by previous researchers.
[3] As we know in the Budker condition by propagating the dense warm relativistic electron beam (WREB) into dilute plasma, the electrons of plasma environment will move away from the range of plasma radius and then ion channel will form. On the other hand, this beam can be focused by the space charge field of the ions, which is called ion focus regime (IFR). In this case the presence of ion channel makes the WREB able to stabile transmit in the plasma. But in this configuration, the beam electrons undergo betatron oscillations can couple with electromagnetic waves (EMW) in the channel. Therefore, to form an effective ion channel to guide the WREB stably transmitted in the space, the density of the WREB and ion channel must be well matched. Under the unstable conditions, the beam electrons can exchange its energy with electromagnetic wave (EMW) and dissipate through radiation. Obviously, in this system the self-fields of the beam electrons and the ion channel effects play an extremely important role in the entire physical process of the REB trajectory.
[4-6] Therefore, investigating these effects on the stability of beam plasma system in order to better understand the mechanism of the microwave radiation, the source of creating electromagnetic waves, the free electron laser using ion channel, the plasma wiggler x-ray, and other plasma radiation sources are important.
[7-12] Moreover, it can also be helpful for understanding the generations of the fast developing high power electromagnetic sources, such as the high power microwaves,
[13] millimeter waves,
[14] and sub-terahertz waves.
[15]