A proof of principle experiment is underway at the UCLA Neptune laboratory to test the concept of generating linearly ramped relativistic electron bunches (rising in density from head to tail followed by a sharp cutoff) by using a sextupole-corrected dogleg section as a bunch compressor. Bunches with this structure have been predicted to be ideal for use as a plasma wakefield drive beam. The di...

The installation of a 3rd harmonic Landau accelerator module is planned at BESSY II to improve the beam lifetime. The passive cavity shall provide an accelerating voltage up to 500 kV for beam currents from 10 to 500 mA. A CESR Phase-III cavity [1], scaled to 1.5 GHz, will be used. The cavity design provides strong damping of higher-order modes by ferrite loads on the beam tubes. A new module, ...

The stability of a beam in an RF accelerating cavity in a storage ring or circular accelerator has been studied by K. Robinsonl* 2 and many others. Robinson has found that under certain assumptions the beam-RF system with no feedback control is stable against “center-of-charge” oscillations if the cavity resonance frequency, wo, lies in restricted ranges. In particular, if ~0 is less than the R...

This study evaluates the dosimetric impact caused by an air cavity located at 2 mm depth from the top surface in a PMMA phantom irradiated by electron beams produced by a Siemens Primus linear accelerator. A systematic evaluation of the effect related to the cavity area and thickness as well as to the electron beam energy was performed by using Monte Carlo simulations (EGSnrc code), Pencil Beam...

As part of the Low-Energy Demonstration Accelerator (LEDA) portion of the Advanced Accelerator Applications (AAA) project we have fabricated and will perform high-power RF tests on Section 2 of the 700MHz Coupled-Cavity Drift-Tube Linac (CCDTL). This CCDTL section contains six, two-gap accelerating cells. This portion of the CCDTL was designed to accelerate the 100-mA, LEDA RFQ proton beam to 7...

A high-intensity continuous-wave (CW) radio frequency quadrupole (RFQ) accelerator is designed for boron neutron capture therapy. The transmission efficiency of a 20-mA proton beam accelerated from 30 keV to 2.5 MeV can reach 98.7% at an operating 200 MHz. dynamics have good tolerance errors. By comparing the high-frequency parameters quadrilateral and octagonal RFQ cross sections, structure fo...

Multipactor discharges are widely observed in the accelerator field, and their suppression has been studied to improve performance. A dielectric-assist accelerating (DAA) cavity is a standing-wave that attains Q-value of over 100,000 at room temperature by using reflection dielectric layer; DAA expected be used with small RF power source high-duty operation. Thus far, maximum field cavities lim...

The IPNS RCS is a rapid cycling synchrotron used to accelerate protons from 50 MeV to 450 MeV, 30 times per second. Currently, two single-gap, ferrite-loaded coaxial cavities, located 180o apart, provide a total peak accelerating voltage of approximately 21 kV over the 2.2 MHz to 5.1 MHz revolution frequency band. An amplifier chain, which includes a 2 kW predriver, a 20 kW driver and a 100 kW ...

Experiments at the FLASH linac at DESY have demonstrated that the Higher Order Modes induced in Superconducting Cavities can be used to provide a variety of beam and cavity diagnostics. The centers of the cavities can be determined from the beam orbit which produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used as a high resolution beam position ...

The crossbar-H-mode (CH) structure is the first superconducting multicell drift tube cavity for the low and medium energy range operated in the H21 mode. Because of the large energy gain per cavity, which leads to high real estate gradients, it is an excellent candidate for the efficient acceleration in high power proton and ion accelerators with fixed velocity profile. A prototype cavity has b...