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Results for “BEAM LIFETIME”

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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring

In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Online multi-objective Bayesian optimization of injection efficiency and beam lifetime with skew quadrupoles at NSLS-II

At NSLS-II, the vertical emittance of electron beam is typically blown up to ~30 pm with a coupling wave to increase beam lifetime during user operation. As more and more insertion devices are added to the storage ring, injection efficiency to the ring drops noticeably in certain machine states, apparently due to degraded dynamic apertures. To help alleviate this issue, we have recently performed online multi-objective Bayesian optimization to increase injection efficiency while maintaining beam lifetime, by adjusting the strengths of 15 skew quadrupoles in non-dispersive sections. We report the results of this optimization effort.

Hidaka, Yoshiteru [Brookhaven]↗
DOE OSTI2011

Measurement of Beam Lifetime and Applications for SPEAR3

Beam lifetime studies for the SPEAR3 storage ring are presented. The three lifetime components are separated with lifetime measurements under various combinations of beam currents and fill patterns and vertical scraper scans. Touschek lifetime is studied with rf voltage scans and with the horizontal or vertical scrapers inserted. The measurements are explained with calculations based on the calibrated lattice model. Quantum lifetime measurements are performed with reduced longitudinal and horizontal apertures, respectively, from which we deduce the radiation energy loss down to a few keV per revolution and the horizontal beam size.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

MULTI-OBJECTIVE ONLINE OPTIMIZATION OF BEAM LIFETIME AT APS

In this paper, online optimization of beam lifetime at the APS (Advanced Photon Source) storage ring is presented. A general genetic algorithm (GA) is developed and employed for some online optimizations in the APS storage ring. Sextupole magnets in 40 sectors of the APS storage ring are employed as variables for the online nonlinear beam dynamics optimization. The algorithm employs several optimization objectives and is designed to run with topup mode or beam current decay mode. Up to 50\% improvement of beam lifetime is demonstrated, without affecting the transverse beam sizes and other relevant parameters. In some cases, the top-up injection efficiency is also improved.

APS↗
DOE OSTI2011

Beam lifetime and limitations during low-energy RHIC operation

The low-energy physics program at the Relativistic Heavy Ion Collider (RHIC), motivated by a search for the QCD phase transition critical point, requires operation at low energies. At these energies, large nonlinear magnetic field errors and large beam sizes produce low beam lifetimes. A variety of beam dynamics effects such as Intrabeam Scattering (IBS), space charge and beam-beam forces also contribute. All these effects are important to understand beam lifetime limitations in RHIC at low energies. During the low-energy RHIC physics run in May-June 2010 at beam {gamma} = 6.1 and {gamma} = 4.1, gold beam lifetimes were measured for various values of space-charge tune shifts, transverse acceptance limitation by collimators, synchrotron tunes and RF voltage. This paper summarizes our observations and initial findings.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Effects of a long low-gap in-vacuum undulator on the impedance and beam lifetime

Possible installation of a long low-gap in-vacuum undulator in the NSLS-II storage ring could result in several impedance-related and beam lifetime issues. High impedance of the low-gap undulator can result in beam instabilities and beam-induced overheating of the undulator itself. These issues have been preliminary studied using analytical formulae, computer simulations and experience of operations with existing in-vacuum undulators. Depending on the device location, the minimum gap and the overall ring-average residual gas pressure, an in-vacuum undulator (IVU) may appreciably shorten the elastic gas scattering component of the beam lifetime. When the latter becomes comparable to the Touschek lifetime, a significant reduction of the total beam lifetime will occur. Here this effect is studied by applying some well-known analytical formulas, as well as insights from NSLS-II operating experience. Finally, the issue of IVU radiation damage also needs to be looked at, and potentially addressed with a dedicated collimation system.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Benchmarking of Touschek Beam Lifetime Calculations for the Advanced Photon Source

Particle loss from Touschek scattering is one of the most significant issues faced by present and future synchrotron light source storage rings. For example, the predicted, Touschek-dominated beam lifetime for the Advanced Photon Source (APS) Upgrade lattice in 48-bunch, 200-mA timing mode is only ~ 2 h. In order to understand the reliability of the predicted lifetime, a series of measurements with various beam parameters was performed on the present APS storage ring. This paper first describes the entire process of beam lifetime measurement, then compares measured lifetime with the calculated one by applying the measured beam parameters. The results show very good agreement.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Transverse Beam Tails and Beam Lifetime in the EIC Electron Storage Ring

For most storage ring design purposes it is sufficient to assume a Gaussian distribution of the electrons in a bunch. However, a more detailed knowledge of the population in the transverse tails beyond a few sigma is necessary to predict the beam lifetime and the synchrotron radiation load in the interaction region due to beam-gas scattering and the beam-beam interaction. This report presents simulations to determine the required vacuum level as well as to serve as input data for detailed synchrotron radiation simulations.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Proton beam lifetime increase with 10- and 12-pole correctors in the Relativistic Heavy Ion Collider

10- and 12-pole correctors were installed in a number of machines and are also considered for future machines. In the Relativistic Heavy Ion Collider (RHIC) 10- and 12-pole correctors exist to correct for the detrimental effects of magnetic field errors in the interaction region magnets. These field errors in conjunction with beam-beam effects and parameter modulations dominate the beam lifetime in polarized proton operation. During the 2009 polarized proton run 10- and 12-pole correctors were set through an iterative procedure, and used for the first time operationally in one of the beams. We report on the procedure to set these high-order multipole correctors, compare the found values with calculated ones, estimate the effect of the new corrector settings on the integrated luminosity, and calculate the effect of both the calculated and experimentally found corrector strengths on the dynamic aperture.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Proton beam lifetime increase with 10- and 12-pole correctors in the Relativistic Heavy Ion Collider

10- and 12-pole correctors were installed in a number of machines and are also considered for future machines. In the Relativistic Heavy Ion Collider (RHIC) 10- and 12-pole correctors exist to correct for the detrimental effects of magnetic field errors in the interaction region magnets. These field errors in conjunction with beam-beam effects and parameter modulations dominate the beam lifetime in polarized proton operation. During the 2009 polarized proton run 10- and 12-pole correctors were set through an iterative procedure, and used for the first time operationally in one of the beams. We report on the procedure to set these high-order multipole correctors, compare the found values with calculated ones, estimate the effect of the new corrector settings on the integrated luminosity, and calculate the effect of both the calculated and experimentally found corrector strengths on the dynamic aperture.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

CONSTRAINTS ON QUASAR LIFETIMES AND BEAMING FROM THE He II Ly{alpha} FOREST

We show that comparisons of He II Ly{alpha} forest lines of sight to nearby quasar populations can strongly constrain the lifetimes and emission geometry of quasars. By comparing the He II and H I Ly{alpha} forests along a particular line of sight, one can trace fluctuations in the hardness of the radiation field (which are driven by fluctuations in the He II ionization rate). Because this high-energy background is highly variable-thanks to the rarity of the bright quasars that dominate it and the relatively short attenuation lengths of these photons-it is straightforward to associate features in the radiation field with their source quasars. Here we quantify how finite lifetimes and beamed emission geometries affect these expectations. Finite lifetimes induce a time delay that displaces the observed radiation peak relative to the quasar. For beamed emission, geometry dictates that sources invisible to the observer can still create a peak in the radiation field. We show that both these models produce substantial populations of 'bare' peaks (without an associated quasar) for reasonable parameter values (lifetimes {approx}10{sup 6}-10{sup 8} yr and beaming angles {approx}< 90 deg.). A comparison to existing quasar surveys along two He II Ly{alpha} forest lines of sight rules out isotropic emission and infinite lifetime at high confidence; they can be accommodated either by moderate beaming or lifetimes {approx}10{sup 7}-10{sup 8} yr. We also show that the distribution of radial displacements between peaks and their quasars can unambiguously distinguish these two models, although larger statistical samples are needed.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Development and Test of Simulation Tools for EIC Beam-Beam Interaction (Final Technical Report)

This final technical report summarizes the work of the Michigan State University (MSU) team supported by grant # DE-SC0018973 awarded by the Office of Nuclear Physics, Department of Energy. The awarded proposal is a joint effort of Brookhaven National Laboratory (BNL, led by Dr. Yun Luo), Lawrence Berkeley National Laboratory (LBNL, led by Dr. Ji Qiang), Thomas Jefferson National Accelerator Facility (TJNAF, led by Dr. Yves Roblin) and MSU (led by Dr. Yue Hao). The MSU personnel supported by the grant include Dr. Yue Hao and Dr. Derong Xu, who is hired as a postdoctoral research fellow. MSU team ‘s work in this proposal focused on the beam dynamics study and numerical simulation of crabbed collision with crab cavities. Analytical calculations and numerous simulations have been done to identify beam dynamics effect out of numerical noises, study the synchro-betatron resonance in the crab crossing scheme, evaluate the effects of non-ideal settings for crab cavity and the effects of the crab crossing noises. The results have been published in journals and as conference proceedings. From the results of the proposal, we gained a clear understanding of the beam-beam interaction in the EIC designs and provided robust countermeasures to possible beam-beam interaction related to beam lifetime reduction, beam emittance growth, beam instabilities, and luminosity degradation, which significantly mitigate the technical risks associated with the EIC accelerator designs.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Beam Loss Simulation and Collimator System Configurations for the Advanced Photon Source Upgrade

The proposed multi-bend achromat lattice for the Advanced Photon Source upgrade (APS-U) has a design emittance of less than 70 pm. The Touschek loss rate is high: compared with the current APS ring, which has an average beam lifetime ~ 10 h, the simulated beam lifetime for APS-U is only ~2 h when operated in the high flux mode (I=200 mA in 48 bunches). An additional consequence of the short lifetime is that injection must be more frequent, which provides another potential source of particle loss. In order to provide information for the radiation shielding system evaluation and to avoid particle loss in sensitive locations around the ring (for example, insertion device straight sections), simulations of the detailed beam loss distribution have been performed. Several possible collimation configurations have been simulated and compared.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Diffusion Dynamics in a Tevatron Store

A separator failure during a store in 2002 led to a drop in luminosity, to increased emittance growth and to a drop in beam lifetimes. We show that a simple diffusion model can be used to explain the changes in beam lifetimes. Emittance growth of beams when they are in collision occurs due to many sources: beam-beam interactions, magnetic nonlinearities, intra-beam scattering, scattering off the residual gas and possibly others. The dynamics of the emittance growth is complicated and it depends strongly on the tunes. It is not always clear that the dynamics can be described by a diffusion process at all particle amplitudes in each beam. However in one store early in Run II, there was a sudden drop in a separator voltage in the Tevatron and the subsequent enhanced emittance growth and intensity lifetime drop could be described by a simple diffusion model. In this report we analyze the luminosity drop, compare the measured value with the expected drop and analyze the change in beam lifetimes. We show how a simple model of diffusive emittance growth and a change in physical aperture provides a quantitative explanation for the change in lifetimes.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Multipole error data analysis for RHIC low-energy operations

In FY10, RHIC operated with gold beams at three different energies below its regular injection energy, namely at $\sqrt{s}$ = 5 GeV, 7.7 GeV, and 11.5 GeV. While beam lifetimes of about 10 minutes were achieved at 11.5 GeV and 7.7 GeV, leading to stable collider operation, beam lifetimes during tests at $\sqrt{s}$ = 5 GeV were only of the order of several seconds. Though space charge effects are a major concern in low energy operations due to the $1/\gamma^2$ scaling of the space charge force, these can effectively be ruled out as the main cause of this abysmal performance because of the tiny bunch intensities of approximately $10^8$ Au/bunch, compared to $10^9$ Au/bunch at the two higher energies. During these 5 GeV tests, large betatron tune spreads were observed, but the extremely short beam lifetime prevented chromaticity measurements. Instead, chromaticities were scanned over a range of 40 units, but to no effect. It was therefore suspected at that time that the large tune spread was caused by higher-order multipole errors in the RHIC magnets.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Multiple error data analysis for RHIC low-energy operations

In FY10, RHIC operated with gold beams at three different energies below its regular injection energy, namely at {radical}s = 5 GeV; 7.7 GeV; and 11.5 GeV: While beam lifetimes of about 10 minutes were achieved at 11.5 GeV and 7.7 GeV; leading to stable collider operation, beam lifetimes during tests at {radical}s = 5 GeV were only of the order of several seconds. Though space charge effects are a major concern in low energy operations due to the 1/{gamma}{sup 2} scaling of the space charge force, these can effectively be ruled out as the main cause of this abysmal performance because of the tiny bunch intensities of approximately 10{sub 8} Au/bunch, compared to 10{sup 9} Au/bunch at the two higher energies. During these 5 GeV tests, large betatron tune spreads were observed, but the extremely short beam lifetime prevented chromaticity measurements. Instead, chromaticities were scanned over a range of 40 units, but to no effect. It was therefore suspected at that time that the large tune spread was caused by higherorder multipole errors in the RHIC magnets.

43 PARTICLE ACCELERATORS↗