We describe the status and initial commissioning of the Visible to Infrared SASE Ampli"er (VISA) experiment. VISA uses a strong focusing 4 m undulator, the Brookhaven National Laboratory ATF linac with an energy of 72 MeV, and a photoinjector electron source. The VISA fundamental radiation wavelength is near 800 nm and the power expected at saturation is near 60 MW. Power, angular and spectral ...

The Facility for Accelerator science and Experimental Tests (FACET) at SLAC provides a high charge, high peak current, sub-picosecond bunched electron beam that is ideal for 0.1 to 2 THz radiation generation via coherent transition radiation. This paper presents preliminary characterization of the terahertz pulses generated by the FACET electron beam. The measured THz frequency content spans fr...

The longitudinal space-charge amplifier has been recently proposed by Schneidmiller and Yurkov as an alternative to the free-electron laser instability for the generation of intense broadband radiation pulses [Phys. Rev. ST Accel. Beams 13, 110701 (2010)]. In this Letter, we report on the experimental demonstration of a cascaded longitudinal space-charge amplifier at optical wavelengths. Althou...

We deduce the equations that describe how polarized radiation is Comptonized by a hot electron gas. Low frequencies are considered, and the equations are expanded to second order in electron velocities. Induced scattering terms are included and a Maxwellian velocity distribution for the electrons is assumed. The special case of an axisymmetric radiation field is also considered, and the corresp...

In a superconductor, in which electrons are paired, the density of unpaired electrons should become zero when approaching zero temperature. Therefore, radiation detectors based on breaking of pairs promise supreme sensitivity, which we demonstrate using an aluminium superconducting microwave resonator. Here we show that the resonator also enables the study of the response of the electron system...

24.1.1 Coherent, Free-Electron Radiation Sources The primary objective of the group is to develop a basic experimental and theoretical understanding of coherent generation by free electrons for wavelengths in the 1 Ym to 10 cm range. Particular emphasis is placed on free electron lasers, Cerenkov sources, relativistic magnetrons, and other novel radiation sources. The experiments are carried ou...

The Landau, Pomeranchuk, Migdal (LPM) effect (suppression of the bremsstrahlung from high energy electron due to a multiple scattering of an emitting electron in dense media) is considered for the case when thickness of a target is of the order or less than the formation length of radiation. The effects of the polarization of a medium and transition radiation are taken into account as well. Qua...

The introduction of a plasma and a strong guide magnetic field in a free electron laser (FEL) slows down the phase velocity of radiation, significantly reducing the requirements on beam energy for generating frequencies below the electron-cyclotron frequency (oi, < oj,). Around plasma resonance (cu, ~ wp), the FEL mode couples to two-stream instability (TSI), attaining a large growth rate, comp...

Investigations of the Smith-Purcell radiation (SPR) were began with non-relativistic electron beams with some unexpected experimental results. Further the experimental investigations were performed with relativistic electron beams for application to beam diagnostics. Large discrepancy between different theoretical models significantly increases the role of experimental studies of this phenomeno...