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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Estimates of Power Radiated by the Beam in Bends of LCLS-II

In the injector region of LCLS-II the bunches pass through bends in the chicanes of the laser heater, of BC1 and BC2, and in the dogleg after the linac. The bunch repetition rate will be high, 1 MHz, and one would like to know the coherent synchrotron radiation (CSR) power radiated in the bends. We are particularly concerned about power that might radiate into cryomodules; however, for completeness we will perform calculations for all the bends in the laser heater, BC1, BC2, and the dogleg. In this note we estimate the CSR power for Gaussian (longitudinal) bunch distributions, using simple free-space and shielded CSR wake models. In the Appendix we repeat the calculations for more realistic bunch shapes obtained by numerical simulation. Finally, for completeness, we also calculate the incoherent synchrotron radiation (ISR) generated in the bends. Even though the ISR power radiated will be much less than the CSR power, it is of special interest because the spectrum reaches to much higher frequencies.

43 PARTICLE ACCELERATORS↗
DOE OSTI2013

A Possible Dechirper Device for the LCLS and LCLS-II

The purpose of this note is to investigate the use of a metallic pipe with small corrugations for passively dechirping, through its wakefield, the LCLS beam. Similar dechirper systems have been tested in Pohang and Brookhaven at relatively low energies (< 100 MeV) and with relatively long bunches (> 1 ps). A recent proposal from RadiaBeam is to build a 2-m dechirper and install it in the LCLS for a GeV, femtosecond beam test. Such a device can be used to either reduce or increase the amount of energy chirp in a short electron bunch prior to the FEL interaction in the undulator, and hence provide a flexible control of the LCLS FEL bandwidth. The results can be used to guide the design of the LCLS-II dechirper, where it is important to remove unwanted electron energy chirp from the LCLS-II superconducting accelerator and to provide independent controls of x-ray properties in each of the two parallel beamlines.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Specifications of the octupole magnets required for the ATF2 ultra-low ß* lattice

The Accelerator Test Facility 2 (ATF2) aims to test the novel chromaticity correction for higher chromaticity lattices as the one of CLIC. To this end the ATF2 ultra-low ß* lattice is designed to vertically focus the beam at the focal point or usually referred to as interaction point (IP), down to 23 nm. However when the measured multipole components of the ATF2 magnets are considered in the simulations, the evaluated spot sizes at the IP are well above the design value. The designed spot size is effectively recovered by inserting a pair of octupole magnets. In this note we address the technical specifications required for these octupole magnets.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Beam Position Detection Along the Collider Arms

A small position monitor is presented here which meets the Collider specifications for the detection of the beam position along the arms. This is a summary of the points worth noting regarding the operation of this detector.

Accelerators↗
DOE OSTI2014

High Energy Colliding Beams; What Is Their Future?

The success of the first few years of LHC operations at CERN, and the expectation of more to come as the LHC’s performance improves, are already leading to discussions of what should be next for both proton-proton and electron-positron colliders. In this discussion I see too much theoretical desperation caused by the so far unsuccessful hunt for what is beyond the Standard Model, and too little of the necessary interaction of the accelerator, experimenter, and theory communities necessary for a scientific and engineering success. Here, I give my impressions of the problem, its possible solution, and what is needed to have both a scientifically productive and financially viable future.

Accelerators↗
DOE OSTI2015

A tunable, linac based, intense, broad-band THz source forpump-probe experiments

We propose an intense THz source with tunable frequency and bandwidth that can directly interact with the degrees of freedom that determine the properties of materials and thus provides a new tool for controlling and directing these ultrafast processes as well as aiding synthesis of new materials with new functional properties. This THz source will broadly impact our understanding of dynamical processes in matter at the atomic-scale and in real time. Established optical pumping schemes using femtosecond visible frequency laser pulses for excitation are extended into the THz frequency regime thereby enabling resonant excitation of bonds in correlated solid state materials (phonon pumping), to drive low energy electronic excitations, to trigger surface chemistry reactions, and to all-optically bias a material with ultrashort electric fields or magnetic fields. A linac-based THz source can supply stand-alone experiments with peak intensities two orders of magnitude stronger than existing laser-based sources, but when coupled with atomic-scale sensitive femtosecond x-ray probes it opens a new frontier in ultrafast science with broad applications to correlated materials, interfacial and liquid phase chemistry, and materials in extreme conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2015

A Massively Parallel Solver for the Mechanical Harmonic Analysis of Accelerator Cavities

ACE3P is a 3D massively parallel simulation suite that developed at SLAC National Accelerator Laboratory that can perform coupled electromagnetic, thermal and mechanical study. Effectively utilizing supercomputer resources, ACE3P has become a key simulation tool for particle accelerator R and D. A new frequency domain solver to perform mechanical harmonic response analysis of accelerator components is developed within the existing parallel framework. This solver is designed to determine the frequency response of the mechanical system to external harmonic excitations for time-efficient accurate analysis of the large-scale problems. Coupled with the ACE3P electromagnetic modules, this capability complements a set of multi-physics tools for a comprehensive study of microphonics in superconducting accelerating cavities in order to understand the RF response and feedback requirements for the operational reliability of a particle accelerator. (auth)

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Study of ultra-low emittance design for Spear3 using longitudinal gradient dipole

Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improved its performance by raising beam current, top-off injection, and smaller emittance. This makes SPEAR3 one of the most productive light sources in the world. Now to further enhance the performance of SPEAR3, we are looking into the possibility of converting SPEAR3 to an ultra-low emittance storage ring within its site constraint.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

CLIC Drive Beam Gun

The Compact Linear Collider (CLIC) is a proposed future electron-positron collider, designed to perform collisions at energies from 0.5 to 5 TeV, with a nominal design optimized for 3 TeV (Dannheim, 2012). CLIC generates three beams: the drive beam, the main electron beam and the positron beam. The drive beam is a high current electron beam that is accelerated in an S-band linac and then decelerated in 12 GHz structures to generate the RF for accelerating the colliding main electron and positron beams. The drive beam employs a high current thermionic DC electron gun. This report explores the optimal anode – cathode geometry as well as analyzes the mechanical and electrical integrity of the gun structure designed by CERN.

43 PARTICLE ACCELERATORS↗