A photocathode-based low-emittance femtosecondbunch electron source is developed in Osaka University to reveal the hidden dynamics of intricate molecular and atomic processes in materials through experimentation such as time-resolved pulse radiolysis or time-resolved electron diffraction. The transverse and longitudinal dynamics of femtosecond electron beam in the photocathode rf gun were studi...

A laser-driven photo-cathode electron gun capable of producing pulsed electron beams of 100 KeV with a duration of 35 ps was constructed as a continuing effort towards a high-brightness superconducting RF injector. Various species of photo-cathodes can be obtained either by ion implantation, CVD or ion enhanced deposition in the preparation chamber attached to the injector. A number of photo-ca...

The feedback system has been developed in KU-FEL linac to stabilize the FEL power fluctuation. The system consists of six 4-button type BPMs and the signal processing system. As the first step, the beam displacement information at the RF-gun section was used for the feedback control to stabilize the electron energy and the vertical beam position at the RF-gun section. As the result the FEL powe...

The electron gun for the SPEAR3 injector operates with a warm thermionic dispenser cathode immersed in a 1.5-cell RF structure. At each injection cycle the gun accelerates several thousand electron bunches up to ~3 MeV during a 2.5us rf pulse. The individual bunches are then compressed by an alpha magnet and a travellingwave chopper selects 3-5 bunches so they don’t cause beam loading to the li...

The BNL electron gun will incorporate a laser-driven photocathode in the wall of a 1 cell RF cavity operated at a peak field of 100 MV/m. Pulses of 4.5-MeV energy, 5-ps width, and 1-nC charge will be produced with very little emittance growth due to the effects of space-charge and nonlinear RF fields. The design of the gun was aided by extensive computer simulation described here.

As part of an international collaboration, the Stanford Linear Accelerator Center (SLAC) klystron group has designed, fabricated and tested a 60 Hz, 3 W, 150 MW klystron built for Deutsches Elektronen Synchrotron (DESY). A test diode with a 535 kV, 700 A electron beam was constructed to verify the gun operation. The first klystron was built and successfully met design specifications. This paper...

A two-stage 500 kV 200-A ferroelectric electron gun has been designed, fabricated, tested, and used in a high power microwave amplifier experiment. We report on the operational characteristics of the gun including measurements of the beam dynamics. The optimum conditions for application of the trigger and its timing are also reported. Faraday cup measurement shows that the beam radius is 4.1 mm...

Particle distribution of the electron beam extracted from a thermionic RF gun in longitudinal phase space is crucial for electron bunch compression. Because space charge effects in the RF gun are not fully understood, an efficient bunch compression scheme employing magnetic chicane or alpha (α-) magnet is not easily designed. In order to measure the distribution in the longitudinal phase space ...

The stability of the photo injector is a key issue for the successful operation of linac based free electron lasers. Several types of jitter can impact the stability of a laser driven RF gun. Fluctuations of the RF launch phase and the cathode laser energy have significant influence on the performance of a high brightness electron source. Bunch charge measurements are used to monitor the stabil...

Gigahertz to terahertz radiation sources based on cold-cathode vacuum electron technology are pursued, because its unique characteristics of instant switch-on and power saving are important to military and space applications. Gigahertz gyrotron was reported using carbon nanotube (CNT) cold-cathode. It is reported here in first time that a fully-sealed CNT cold-cathode 0.22 THz-gyrotron is reali...