A novel compact time-resolved electron diffractometer has been built with the primary goal of studying the ultrafast molecular dynamics of photoexcited gas-phase molecules. Here, we discuss the design of the electron gun, which is triggered by a Ti:Sapphire laser, before detailing a series of calibration experiments relating to the electron-beam properties. As a further test of the apparatus, i...

A project is underway that aims to generate attosecond pulses via high-harmonic generation in rare gases, driven by extremely short and highly intense from free-electron-laser oscillators. For this purpose, it has been planned a new photocathode RF gun, dedicated high-bunch-charge operation, will be installed at the KU-FEL (Kyoto University Free Electron Laser) oscillator facility. In study, gu...

Femtosecond electron bunches with keV energies and eV energy spread are needed by condensed matter physicists to resolve state transitions in carbon nanotubes, molecular structures, organic salts, and charge density wave materials. These semirelativistic electron sources are not only of interest for ultrafast electron diffraction, but also for electron energy-loss spectroscopy and as a seed for...

* Work supported by the U. S. Department of Energy at NRL under contracts DE-AI02-93ER40799 and DE-AI02-94ER54232, at U. Md. under DE-FG02-92ER54178 and DE-FG02-94ER40855, and at the HIFVNL under DE-AC03-76SF00098 and W-7405-Eng-48. Abstract An important feature of the UMER experimental program [1,2] is the continuing use of comparison between computer simulation and experimental measurement. T...

Laser driven plasma waves have up to now been considered exclusively as second stage accelerators. Conventional finacs are used in this case as the first stage of acceleration to inject MeV electrons into the plasma. This paper shows it to be advantageous to instead use laser wake fields in the first stage for greater simplicity and better emittance. The concept presented makes this possible wi...

The SLC thermionic gun and electron source produce a beam of up to 15 x 10” ein a single S-band bunch. A 170 keV, 2 ns FWHM pulse out of the gun is compressed by means of two subharmonic buncher cavities followed by an S-band buncher and a standard SLAC accelerating section. Ceramic gaps in the beam pipe at the output of the gun allow a measure of the beam intensity and timing. A measurement at...

The Advanced Photon Source (APS) photocathode rf gun is the primary beam source for the APS Low-Energy Undulator Test Line (LEUTL) free-electron laser (FEL) experiment. In the current operating regime of LEUTL, peak current has been the dominant factor in determining FEL performance. As LEUTL’s operational wavelength is reduced, however, the beam emittance will play an increasingly important ro...

Pulsed laser deposition (PLD) has been proposed several years ago as a suitable technique to deposit a pure Mg film over a radio frequency (rf ) gun Cu backflange in order to obtain a high efficiency photocathode surface for the generation of high brightness electron beams. In this paper we report preliminary experimental results on the emission properties of a PLD grown Mg film within the high...

Electron beams with an energy range of 10keV at 2A requiring intensity modulation with bandwidth from 50kHz 7.5MHz pose an interesting problem to the RF designer. Driving the extraction electrode of an electron gun can be a challenge with these requirements. The straight forward approach is the construction of a vacuum tube, single ended amplifier capable of delivering the anode voltage to the ...