A5006365272- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Gyrotron and Vacuum Electronics Research
- Nuclear reactor physics and engineering
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- Optical Systems and Laser Technology
- Muon and positron interactions and applications
- Laser Design and Applications
- Advanced X-ray Imaging Techniques
- Particle physics theoretical and experimental studies
- Distributed and Parallel Computing Systems
- Laser-Matter Interactions and Applications
- Ion-surface interactions and analysis
- Photocathodes and Microchannel Plates
- Pulsed Power Technology Applications
- Radiation Detection and Scintillator Technologies
- Engineering Applied Research
- Electron and X-Ray Spectroscopy Techniques
Oak Ridge National Laboratory
2014-2023
University of Tennessee at Knoxville
2017-2018
Fermi Research Alliance
2015
Muons (United States)
2015
Spallation Neutron Source
2004-2008
Siberian Federal University
2007
Tech-X (United Kingdom)
2007
Budker Institute of Nuclear Physics
2003
The method of H- photoionization is interesting for laser assisted charge exchange injection. In this paper, the model and computation negative hydrogen ion by using strong lasers considered. development work motivated pure photodetachment electron from when it not convenient or possible to use stripping magnet. Herein we develop a calculation high efficiency time dependent wave equation with application powerful lasers. We compare precise simplified through linear cross section interaction....
This Letter presents the first complete six dimensional phase space measurement of a beam in an accelerator. The was made on Spallation Neutron Source Beam Test Facility. data reveal previously unknown correlations distribution that are not visible lower dimensionality measurements. shown to be intensity dependent.
Thin carbon foils are used as strippers for charge exchange injection into high intensity proton rings. However, the stripping become radioactive and produce uncontrolled beam loss, which is one of main factors limiting power in Recently, we presented a scheme laser an ${\mathrm{H}}^{\ensuremath{-}}$ Spallation Neutron Source (SNS) ring. First, atoms converted to ${\mathrm{H}}^{0}$ by magnetic field, then excited from ground state upper levels laser, states protons field. In this paper...
We report on an experiment in which a negative hydrogen ion beam the Spallation Neutron Source (SNS) linear accelerator was replaced with of protons similar size and dynamics. Fractional loss superconducting part SNS measured to be at least $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ for ${\mathrm{H}}^{\ensuremath{-}}$ beam, it order magnitude lower protons. Also has stronger dependence intensity than proton beams. These measurements verify recent theoretical explanation...
This Letter reports on the first demonstration of laser-assisted ${\mathrm{H}}^{\ensuremath{-}}$ charge exchange for microsecond duration beam pulses. Laser-assisted injection is a breakthrough technology that overcomes long-standing limitations associated with traditional method producing high intensity, time structured beams protons in accelerators via use carbon foils injection. The central theme this experiment novel techniques reduce laser power requirement to allow efficiency stripping...
A high peak-power Q-switched laser has been used to monitor the ion beam profiles in superconducting linac at Spallation Neutron Source (SNS). The suffers from position drift due movement, vibration, or thermal effects on optical components 250-meter long transport line. We have designed, bench-tested, and implemented a stabilization system by using an Ethernet CMOS camera, computer image processing analysis, piezo-driven mirror platform. can respond frequencies up 30 Hz with detection...
Laser-assisted stripping is a novel approach to ${\mathrm{H}}^{\ensuremath{-}}$ charge exchange that overcomes long-standing limitations associated with the traditional, foil-based method of producing high-intensity, time-structured beams protons. This paper reports on first successful demonstration laser technique for microsecond duration beams. The experiment represents factor 1000 increase in stripped pulse compared previous proof-of-principle demonstration. central theme implementation...
The U.S. Spallation Neutron Source (SNS) now operates with ∼1 MW of beam power to target the near-term goal delivering 1.4 MW. Plans are being considered incorporate a second station into facility which will require ∼2.8 power. Presently, H− pulses (∼1 ms, 60 Hz) produced by an RF-driven, Cs-enhanced, multi-cusp ion source injects RFQ (Radio Frequency Quadrupole) accelerator that, in turn, feeds SNS Linac. Currently source/RFQ system delivers ∼35 mA pulsed current linac is mostly sufficient...
The Oak Ridge National Laboratory operates the Spallation Neutron Source, consisting of a H− ion source, 1 GeV linac and an accumulator ring. accumulated <1 μs-long, ∼35 A beam pulses are extracted from ring at 60 Hz directed onto liquid Hg target. Spalled neutrons to ∼20 world class instruments. Currently, facility routinely with ∼1.2 MW average power, which soon will be raised 1.4 MW. future upgrade second target station calls for raising power 2.8 This paper describes status two...
Utilizing noninvasive 2D scans with laser wires, we tomographically reconstructed the 4D transverse phase space distribution of a 1-GeV hydrogen ion (i.e., ${\mathrm{H}}^{\ensuremath{-}}$) beam during operation. The tomography is based on two new advances. First, extended formulation maximum entropy to take projections as input and derived theoretical results relevant our application. Second, introduced method ``perpendicular scans'' obtain cross-plane information from wire emittance...
This paper presents a scheme for three-step laser-based stripping of an ${\mathrm{H}}^{\ensuremath{-}}$ beam charge exchange injection into high-intensity proton ring. First, atoms are converted to ${\mathrm{H}}^{0}$ by Lorentz in strong magnetic field, then neutral hydrogen excited from the ground state upper levels laser, and remaining electron, now more weakly bound, is stripped field. The energy spread particles gives rise Doppler broadened absorption linewidth, which makes inefficient...
The U.S. Spallation Neutron Source (SNS) is a state-of-the-art neutron scattering facility delivering the world's most intense pulsed beams to wide array of instruments which are used conduct investigations in many fields science and engineering. Neutrons produced by spallation liquid Hg due bombardment short (∼1µs), (∼35 A) pulses protons delivered at 60 Hz from storage ring fed high-intensity, 1 GeV H− LINAC. This has operated almost continuously since 2006, with ion source performance...
The front-end systems (FES) of the spallation neutron source project are being built by Berkeley Lab and will deliver a pulsed 40 mA H− ion beam at 2.5 MeV energy to subsequent drift-tube linac. FES accelerator components comprise rf driven, volume-production, cesium-enhanced, multicusp source; an electrostatic low-energy transport (LEBT) that includes provisions for transverse focusing, steering, chopping; radio-frequency quadrupole accelerator; medium-energy line. challenges LEBT design...
A halo generation mechanism in the nonperiodic lattices such as SNS (Spallation Neutron Source) linac MEBT [medium-energy beam transport between radio-frequency quadrupole and DTL (drift tube linac)] is reported. We find that nonlinear space charge force resulting from large transverse eccentricity $\ensuremath{\sim}2:1$ $\ensuremath{\sim}1.6\mathrm{m}$-long chopper section responsible for formation. As a result, distribution, based on front end emittance measurements multiparticle...
A new method of measuring the rms longitudinal Twiss parameters a beam in linear accelerators is presented. It based on using sum signals from position monitors sensitive to charge distribution bunch. The applicability demonstrated superconducting section Oak Ridge Spallation Neutron Source accelerator. results are compared direct measurement bunch profiles an interceptive shape monitor linac warm same Limitations discussed. fast and simple, can be used obtain initial for matching where...
The physics interest in a luminosity upgrade of RHIC requires the development cooling-frontier facility. Detailed calculations were made electron cooling stored beams. This has been followed by beam dynamics simulations to establish feasibility creating necessary beam. accelerator will be superconducting Energy Recovery Linac (ERL). An intensive experimental R&D program engages various elements accelerator, as described 24 contributions 2007 PAC.
The Spallation Neutron Source (SNS) radio-frequency quadrupole (RFQ) had resonance control instabilities at duty factors higher than approximately 4%. Systematic investigations have been carried out to understand the cause of instability and ensure operational stability RFQ. most critical source is revealed be an interaction between hydrogen released by beam bombardments RFQ rf field resulting in a discharge, which consumes additional power could operate unstable region. This paper reports...
The electron beam probe method was suggested for measuring profiles in high power beams. In this method, deflection of a low energy by the collective field intensity is measured. charge density can be restored under certain conditions or estimated various mathematical techniques. We studied feasibility using SNS accumulator ring computer simulations diagnostic setup. Realistic proton distributions were used simulations. Several profile calculation techniques explored and results are reported paper.
A new scheme with sequential resonant excitation for laser assisted charge exchange injection of ${\mathrm{H}}^{\ensuremath{-}}$ beams is proposed. In contrast the one step scheme, proposed requires significantly less power high efficiency stripping. It also provides greater flexibility in choice wavelength a given beam energy and extends range energies where stripping can be effectively applied. Calculations experimental plans 1.0 GeV 1.3 at Spallation Neutron Source are presented. Results...
The U.S. Spallation Neutron Source (SNS) is a state-of-the-art neutron scattering facility delivering the world's most intense pulsed beams to wide array of instruments, which are used conduct investigations in many fields engineering, physics, chemistry, material science, and biology. Neutrons produced by spallation liquid Hg bombardment short (∼1 µs), (∼35 A) pulses protons delivered at 60 Hz an accumulator ring fed high-intensity, 1 GeV, H- LINAC (linear accelerator). This has operated...
A laser wire ion beam profile monitor system has been developed at the Spallation Neutron Source accelerator complex. The uses a single source to measure horizontal and vertical profiles of pulsed hydrogen (H(-)) along 230 m long superconducting linac, which accelerates H(-) from 200 MeV 1 GeV. In this paper, we describe optics requirement for system, performance measurement, effects parameters on measurement reliability. result provides practical guideline development large-scale,...
Charge exchange injection is the standard mechanism used to accumulate short, intense pulses of proton beams from an ${\mathrm{H}}^{\ensuremath{-}}$ injector into a synchrotron. Historically, this process has relied on foils remove two electrons ${\mathrm{H}}^{\ensuremath{-}}$, technique that been successfully employed for beam powers up 1.4 MW. However, such are known sublimate beyond threshold power density, requiring development another stripping technology does not have same limitation....