The Generation of Coherent and Tunable Terahertz Radiation from Plasma Modulated Electron Beams

Terahertz (THz) radiation based technological solutions have applications in many areas including information and communication technology, biology, medical sciences, non-destructive detection and security. With the development of accelerator technologies around the world, there has been a growing interest in the generation of THz radiation driven by a linear accelerator (LINAC). The crucial part in the generation of the tunable THz radiation is the production of microbunched electron beams with picosecond (ps) and sub-ps periodicity. A long electron beam propagating through a plasma channel can be modulated and divided into a train of microbunches, with the periodicity defined by the plasma frequency. We proposed a method of microbunched beam conditioning to allow Smith-Purcell THz radiation generation. The great advantage of the beam plasma modulation is its simplicity, as the microbunch periodicity can be tuned by changing the gas pressure in a plasma capillary and thus the plasma density and plasma frequency. We show that this approach has the potential to generate coherent and tunable THz radiation.