132 research outputs found
Beyond the RF photogun
No full textLaser-triggered switching of MV DC voltages enables acceleration gradients an
order of magnitude higher than in state-of-the-art RF photoguns. In this way
ultra-short, high-brightness electron bunches may be generated without the use
of magnetic compression. The evolution of the bunch during the critical initial
part of the acceleration trajectory, the ’pancake’ regime, where the space-charge
induced deterioration is most severe, is investigated using a simple, but effective
analytical model. We find an expression for the maximally achievable peak current
that does not depend on the bunch charge. An expression for the normalized
emittance is derived, which allows us to calculate the optimal beam radius. It
is shown that both the peak current and the transverse emittance required for
the most challenging applications can be attained without magnetic compression,
if acceleration gradients of 1 GV/m can be realized. The results are confirmed
by simulations with the gpt code, assuming a 1 GV/m acceleration field and a
50 fs laser pulse, generating 100 pC of charge. The model is complementary to
simulations in the sense that it supplies useful scaling laws and improved understanding
of the physics involved. Interestingly, we find that the highest brightness
is achieved with the shortest photoemission laser pulses
Performance simulation and parameter optimization for high gain short wavelength FEL amplifiers
No full textRecommended from our members
The Beam Break-Up Numerical Simulator
No full textBeam Break-Up (BBU) is a severe constraint in accelerator design, limiting beam current and quality. The control of BBU has become the focus of much research in the design of the next generation collider, recirculating and linear induction accelerators and advanced accelerators. Determining the effect on BBU of modifications to cavities, the focusing elements or the beam is frequently beyond the ability of current analytic models. A computer code was written to address this problem. The Beam Break-Up Numerical Simulator (BBUNS) was designed to numerically solve for beam break-up (BBU) due to an arbitrary transverse wakefield. BBUNS was developed to be as user friendly as possible on the Cray computer series. The user is able to control all aspects of input and output by using a single command file. In addition, the wakefield is specified by the user and read in as a table. The program can model energy variations along and within the beam, focusing magnetic field profiles can be specified, and the graphical output can be tailored. In this note we discuss BBUNS, its structure and application. Included are detailed instructions, examples and a sample session of BBUNS. This program is available for distribution. 50 refs., 18 figs., 5 tabs
Design Considerations for a High-Efficiency High-Gain Free-Electron Laser for Power Beaming
No full textDesign Considerations for a High-Efficiency High-Gain Free-Electron Laser for Power Beaming
No full text
Chirped pulse amplification at VISA-FEL
No full textChirped beam manipulations are of the great interest to the free electron laser (FEL) community as potential means of obtaining ultra short X-ray pulses. The experiment is under way at the accelerator test facility (ATF) at Brookhaven National Laboratory (BNL) to study the FEL process limits with the under-compressed chirped electron beam. High gain near-saturation SASE operation was achieved with the strongly chirped beam (∼2.8% head-to-tail). The measured beam dynamics and SASE properties are presented, as well as the design parameters for the next round of experiment utilizing the newly installed UCLA/ATF chicane compressor. © 2004 Elsevier B.V. All rights reserved
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