Super-radiant Smith–Purcell radiation from periodic line charges

Femtosecond response time measurements of a Cs2Te photocathode

“…That is why consideration of a simpler approach to generate short electron bunches or even pre-bunched electron beams directly illuminating a photocathode with femtosecond duration laser pulses become attractive. The application of such a beam is very wide since it can be used to generate an intense spectrum-tunable THz pulses, give enhancement to radiation emission [14,15] and also can be used for resonant excitation of the wakefields in plasma and dielectric wakefield accelerators [16,17]. The important properties of this pre-bunched beam could be continuously variable time separation between micro bunches, square envelope and amplitude modulation possibility within the micro-pulse sequence.…”

Special Smith–Purcell radiation from an open resonator array

“…where λ is the radiation wavelength, θ (shown in figure 1) indicates the radiation direction, L is the structural period, β is the ratio of the beam velocity to light velocity, and n is a negative integer that indicates the harmonic order. More recently, the Smith-Purcell free electron laser (SP-FEL) [6][7][8], which is the coherent SPR from premodulated electron bunches (generated previously by the accelerator or by the beam-wave interaction on the periodic surface), has been extensively studied for its potential in generating radiation that can not be easily obtained by other methods, especially for terahertz (THz) wave generation [9,10]. In SP-FEL, the SPR becomes coherent in some specific directions, where the SPR frequency is harmonic of bunching frequency, and the radiation intensity is remarkably increased since it is proportional to the square of the bunch number.…”