461 research outputs found
Simulation of Coherent Synchrotron Radiation Emission from Rotating Relativistic Electron Layers
The electromagnetic radiation of a rotating relativistic electron layers is
studied numerically using particle-in-cell simulation. The results of the
simulation confirm all relevant scaling properties predicted by theoretical
models. These models may turn out to be important for the understanding of the
coherent synchrotron radiation (CSR) instability that may occur in systems as
diverse as particle accelerators radio pulsars.Comment: 4 pages, 5 figures, one new figure, corrected minor errors, accepted
for publication in Physical Review
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Infrared single spike pulses generation using a short period superconducting tape undulator at APEX
We report on the possibility of constructing an infrared FEL by combining a novel design super-conducting undu-lator developed at LBNL with the high brightness beam from the APEX injector facility. Calculations show that the resulting FEL is expected to deliver a saturated power of over a MW within a âŒ4 m undulator length when operating in Self-Amplified-Spontaneus-Emission mode, with a single-spike of coherent radiation at ⌠2 ÎŒm wavelength. The sub-cm undulator periods, associated with the relatively low energy of the APEX beam (20-25 MeV), forces the FEL to operate in a regime with unusual and interesting characteristics. The alternative option of laser seeding the FEL is also briefly examined, showing the potential to reduce the saturation length even further
Single shot cathode transverse momentum imaging in high brightness photoinjectors
In state of the art photoinjector electron sources, thermal emittance from photoemission dominates the final injector emittance. Therefore, low thermal emittance cathode developments and diagnostics are very important. Conventional thermal emittance measurements for the high gradient gun are time-consuming and thus thermal emittance is not measured as frequently as quantum efficiency during the lifetime of photocathodes, although both are important properties for the photoinjector optimizations. In this paper, a single shot measurement of photoemission transverse momentum, i.e., thermal emittance per rms laser spot size, is proposed for photocathode rf guns. By tuning the gun solenoid focusing, the electrons' transverse momenta at the cathode are imaged to a downstream screen, which enables a single shot measurement of both the rms value and the detailed spectra of the photoelectrons' transverse momenta. Both simulations and proof of principle experiments are reported
CTF3: Design of Driving Beam Combiner Ring
In CTF3 the beam compression of the driving beam structure between the main linac and the decelerating section is obtained with a delay loop and a combiner ring which increase the pulse current by a factor 10. The design of the combiner ring is presented. Tunable isochronicity condition, corrected up to second order, should assure preservation of the correlation in the longitudinal phase space during the compression. Path-length tuning devices are included in the combiner ring layout to compensate for orbit variations
Benefits of Artificially Generated Gravity Gradients for Interferometric Gravitational-Wave Detectors
We present an approach to experimentally evaluate gravity gradient noise, a
potentially limiting noise source in advanced interferometric gravitational
wave (GW) detectors. In addition, the method can be used to provide sub-percent
calibration in phase and amplitude of modern interferometric GW detectors.
Knowledge of calibration to such certainties shall enhance the scientific
output of the instruments in case of an eventual detection of GWs. The method
relies on a rotating symmetrical two-body mass, a Dynamic gravity Field
Generator (DFG). The placement of the DFG in the proximity of one of the
interferometer's suspended test masses generates a change in the local
gravitational field detectable with current interferometric GW detectors.Comment: 16 pages, 4 figure
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Proposal for a High-Brightness Pulsed Electron Source
We propose a novel scheme for a high-brightness pulsed electron source, which has the potential for many useful applications in electron microscopy, inverse photo-emission, low energy electron scattering experiments, and electron holography. A description of the proposed scheme is presented
High Sensitivity Accelerometers for High Performance Seismic Attenuators
We present concepts and features of a new horizontal accelerometer whose mechanical design and machining process aim to improve the sensitivity in the frequency region between 10 mHz and 1 Hz. The expected sensitivity, less than 10^(â11) m/s^2/âHz around 100 mHz, is a couple of orders of magnitude below the state of art limits. This accelerometer could be integrated in the active control of the LIGO II mirror seismic isolators
Overview of Advanced LIGO Adaptive Optics
This is an overview of the adaptive optics used in Advanced LIGO (aLIGO),
known as the thermal compensation system (TCS). The thermal compensation system
was designed to minimize thermally-induced spatial distortions in the
interferometer optical modes and to provide some correction for static
curvature errors in the core optics of aLIGO. The TCS is comprised of ring
heater actuators, spatially tunable CO laser projectors and Hartmann
wavefront sensors. The system meets the requirements of correcting for nominal
distortion in Advanced LIGO to a maximum residual error of 5.4nm, weighted
across the laser beam, for up to 125W of laser input power into the
interferometer
Overview of Advanced LIGO Adaptive Optics
This is an overview of the adaptive optics used in Advanced LIGO (aLIGO), known as the thermal compensation system (TCS). The TCS was designed to minimize thermally induced spatial distortions in the interferometer optical modes and to provide some correction for static curvature errors in the core optics of aLIGO. The TCS is comprised of ring heater actuators, spatially tunable CO_2
laser projectors, and Hartmann wavefront sensors. The system meets the requirements of correcting for nominal distortion in aLIGO to a maximum residual error of 5.4 nm rms, weighted across the laser beam, for up to 125 W of laser input power into the interferometer
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Absolute Bunch Length Measurements at the ALS by Incoherent Synchrotron Radiation Fluctuation Analysis
By analyzing the pulse to pulse intensity fluctuations of the radiation emitted by a charge particle in the incoherent part of the spectrum, it is possible to extract information about the spatial distribution of the beam. At the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory, we have developed and tested a simple scheme based on this principle that allows for the absolute measurement of the bunch length. A description of the method and the experimental results are presented
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