The generation of high intensity coherent radiation m the soft X-ray region from a free electron laser will require the FEL to operate in the high gam or collective instability regime. In this mode of operation, which does not require a cavity resonator, the radiation field grows exponentially along the undulator until nonlinear effects bring on saturation . We discuss the conditions that the e...

The existence of reverse Cherenkov radiation for surface plasmons is demonstrated analytically. It is shown that in a metal-insulator-metal (MIM) waveguide, surface plasmon polaritons (SPPs) excited by an electron moving at a speed higher than the phase velocity of SPPs can generate Cherenkov radiation, which can be switched from forward to reverse direction by tuning the core thickness of the ...

A relativistic/QED theory of light pressure on electrons by an isotropic, in particular blackbody radiation predicts thermalization rates of free electrons over entire span of energies available in the lab and the nature. The calculations based on the QED Klein-Nishina theory of electron-photon scattering and relativistic Fokker-Planck equation, show that the transition from classical (Thompson...

We present data on emission of K-shell radiation from Ti foils irradiated with subpicosecond pulses of second harmonic radiation (527 nm) from the TARANIS laser system at intensities of up to 10(18) W cm(-2). The data are used to demonstrate that a resonance absorption type mechanism is responsible for absorption of the laser light and to estimate fast electron temperatures of 30-60 keV that ar...

At present, the linac-based SASE process is the most promising approach to reaching x-ray wavelengths with a free-electron laser. In the Self-Amplified-SpontaneousEmission process the spontaneous radiation is amplified in the single pass of an electron beam through an undulator, and no mirrors are required. This is an essential requirement for x-ray FELs, since the reflectivity of mirrors decre...

The characteristics of the synchrotron radiation generated by an electron beam in bending magnets, planar undulators and wiggler magnets are derived, with emphasis on the spectral flux, brilliance, and power densities. The interaction of the electron beam with the insertion device field is discussed in terms of closed orbit distortion, tune shift and non-linear effect. The technology of permane...

Seeded single pass free-electron lasers are promising coherent, short-duration, and intense light sources, from the visible to x rays. Operated with adjustable undulators, they are also a unique device for providing fully variable polarized radiation. We report here the first seeding of helical undulators with a variable polarized source. We demonstrate that the adjustment of the seed polarizat...

A Transition Radiation Detector (TRD) has been designed to improve the electron identification and trigger capability of the ALICE experiment at the Large Hadron Collider (LHC) at CERN. We present results from tests of a prototype of the TRD concerning pion rejection for different methods of analysis over a momentum range from 0.7 to 2 GeV/c. We investigate the performance of different radiator...

Pronounced resonant absorption and frequency dispersion associated with an excitation of collective 2D plasmons have been observed in terahertz (0.5-4THz) transmission spectra of grating-gate 2D electron gas AlGaN/GaN HEMT (high electron mobility transistor) structures at cryogenic temperatures. The resonance frequencies correspond to plasmons with wavevectors equal to the reciprocal-lattice ve...

We described here the way of production of ≤ 100 fs bursts of X and gamma radiation by Compton backscattering of a laser bunch which have been swept along the electron trajectory. In the method described the time duration of the secondary radiation does not depend on electron bunch length and is shorter than duration of the primary laser bunch by factor 1/ –the number of resolved spots of sweep...