Superradiance pulse duration by molecular nitrogen ions in air laser plasma

The results of study of superradiance pulse duration by molecular nitrogen ions in air for various focusing conditions of femtosecond radiation pulse with a wavelength of 950 nm are presented. Parameters of active medium are analyzed and mechanism for the formation of picosecond superradiance pulse at femtosecond seed duration is proposed.

Использование импульсов микроволнового сверхизлучения для высокоградиентного ускорения электронов в цилиндрическом волноводе с диэлектрической вставкой

We theoretically study the acceleration of electrons by a 38-GHz subnanosecond superradiance pulse with a 3-GW peak power in a cylindrical waveguide with an annular dielectric insert. It is shown that the energy gain and the accelerating gradient depend on the dielectric constant of the insert, namely, the energy gain decreases and the maximum accelerating gradient increases with increasing the dielectric constant. For an electron with an initial energy of 300 keV, the maximum accelerating gradient reaches 120 MV / m with an energy gain of 7.2 MeV in a waveguide with a polystyrene insert ( = 2.53) and 220 MV / m with an energy gain of 4.5 MeV in a waveguide with a quartz insert ( = 3.81).

Генерация предельно коротких импульсов терагерцового излучения на основе сверхизлучения трехуровневой резонансной среды

The possibility of generating extremely short pulses of terahertz (THz) radiation due to superradiance - collective spontaneous emission of stopped polarization of a thin layer of a three-level resonant medium excited by a pair of attosecond (or femtosecond) pulses is studied theoretically. The source of a terahertz pulse is a pulse of stopped nonlinear polarization of the medium, which occurs in the interval between its excitation and de-excitation. The case of a three-level medium with equidistant energy levels (as in a quantum harmonic oscillator), the transition frequency of which lies in the THz range, is considered. The influence of the populations of the excited levels of the medium on the shape of the terahertz superradiance pulse is discussed.