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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

An Improved Green's Function for Ion Beam Transport

Ion beam transport theory allows testing of material transmission properties in the laboratory environment generated by particle accelerators. This is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are the main emphasis of the present work. In consequence, an analytic solution of the linear Boltzmann equation is pursued in the form of a Green's function allowing flexibility in application to a broad range of boundary value problems. It has been established that simple solutions can be found for the high charge and energy (HZE) by ignoring nuclear energy downshifts and dispersion. Such solutions were found to be supported by experimental evidence with HZE ion beams when multiple scattering was added. Lacking from the prior solutions were range and energy straggling and energy downshift with dispersion associated with nuclear events. Recently, we have found global solutions including these effects providing a broader class of HZE ion solutions.

Tweed, J.↗
NASA NTRS2004

An improved Green's function for ion beam transport

Ion beam transport theory allows testing of material transmission properties in the laboratory environment generated by particle accelerators. This is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are the main emphasis of the present work. In consequence, an analytic solution of the linear Boltzmann equation is pursued in the form of a Green's function allowing flexibility in application to a broad range of boundary value problems. It has been established that simple solutions can be found for high charge and energy (HZE) ions by ignoring nuclear energy downshifts and dispersion. Such solutions were found to be supported by experimental evidence with HZE ion beams when multiple scattering was added. Lacking from the prior solutions were range and energy straggling and energy downshift with dispersion associated with nuclear events. Recently, we have found global solutions including these effects providing a broader class of HZE ion solutions. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

NASA Center LaRC↗
DOE OSTI2018

Optimizing beam transport in rapidly compressing beams on the neutralized drift compression experiment-II

The Neutralized Drift Compression Experiment-II (NDCX-II) is an induction linac that generates intense pulses of 1.2 MeV helium ions for heating matter to extreme conditions. Here, we present recent results on optimizing beam transport. The NDCX-II beamline includes a 1-m-long drift section downstream of the last transport solenoid, which is filled with charge-neutralizing plasma that enables rapid longitudinal compression of an intense ion beam against space-charge forces. The transport section on NDCX-II consists of 28 solenoids. Finding optimal field settings for a group of solenoids requires knowledge of the envelope parameters of the beam. Imaging the beam on the scintillator gives the radius of the beam, but the envelope angle is not measured directly. We demonstrate how the parameters of the beam envelope (radius, envelop angle, and emittance) can be reconstructed from a series of images taken by varying the B-field strengths of a solenoid upstream of the scintillator. We use this technique to evaluate emittance at several points in the NDCX-II beamline and for optimizing the trajectory of the beam at the entry of the plasma-filled drift section.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Optimization of a buncher for High Energy H- Beam Transport [Slides]

Accelerators and beam transport systems typically contain numerous beamline devices, diagnostics, system study, and upgrade. Routinely TRACE, MADX and TRANSPORT codes are used for the beam envelope prediction and optimization. Unknown problems of accelerators and beam-transport are addressed based on R&D, such as LFB voltage variation effect study. A nominal diagnostic have used in non-traditional beam transport path to address scientific question (such as use of a BPM in the air). High energy beam operation is a methodical process and routine R&D is required to maintain high standards to deliver beam.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Experimental improvement of 750-keV H - beam transport at LANSCE Accelerator Facility

The 750-keV low-energy beam transport of the Los Alamos Neutron Science Center (LANSCE) linac consists of two independent beam lines that facilitate simultaneous injection of H + and H - beams into the linear accelerator. The efficiency of beam transport within this structure is largely controlled by the effects of space-charge neutralization. In this study, we report a series of experiments that were performed to determine the level, as well as the required timescale for the onset of beam space charge neutralization. Measurements performed along the structure indicate significant variation of neutralized space charge beam dynamics in the beamline, and the corresponding results have been used to substantially improve beam transport with diminished beam losses. Finally, the analysis of experimental and theoretical data employed in optimization of beam performance in the transport line is discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Beam transport and space charge compensation strategies (invited)

The transport of intense ion beams is affected by the collective behavior of this kind of multi-particle and multi-species system. The space charge expressed by the generalized perveance dominates the dynamical process of thermalisation, which leads to emittance growth. To prevent changes of intrinsic beam properties and to reduce the intensity dependent focusing forces, space charge compensation seems to be an adequate solution. In the case of positively charged ion beams, electrons produced by residual gas ionization and secondary electrons provide the space charge compensation. The influence of the compensation particles on the beam transport and the local degree of space charge compensation is given by different beam properties as well as the ion beam optics. Especially for highly charged ion beams, space charge compensation in combination with poor vacuum conditions leads to recombination processes and therefore increased beam losses. Strategies for providing a compensation-electron reservoir at very low residual gas pressures will be discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

A holistic approach to the optimization of neutron beam transport at the LANSCE facility

An advanced neutron beam collimation system has been developed as part of an effort to optimize neutron beam transport at the Weapons Neutron Research (WNR) Facility, located within the Los Alamos Neutron Science Center (LANSCE). The goal of this work was to develop and demonstrate techniques to tailor neutron delivery in order to provide maximum available flux on sample with a specific beam profile, while simultaneously reducing unwanted background. A holistic approach was taken, upgrading the facility spallation target, facility metrology infrastructure, and flight path shutter insert to support the implementation of this advanced collimation system. Here, modern instruments and software were employed to conduct facility surveys, characterization of as-built geometry of critical components, 3D ray tracing and neutron transport calculations. Beam images and flux measurements were acquired after installation to evaluate the performance of the collimation system and to demonstrate consistent agreement with MCNP simulations which showed an 87% increase of flux on sample while providing suppression of background neutron impingement on the sample frame by 10 3 .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Prototyping of beam position monitor for medium energy beam transport section of RAON heavy ion accelerator

A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, development of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Concatenated analyses of phase space microbunching in high brightness electron beam transport

Microbunching instability (MBI) has been a challenging issue in high-brightness electron beam transport for modern accelerators. The existing theoretical formulation of MBI for recirculating accelerators is based on the single-pass analysis. For multi-pass recirculation or a long beam transport line, the intuitive way of quantifying MBI by successive multiplication of individual scalar amplification gains from subsections of a beamline was found to underestimate the effect. More thorough analyses based on concatenation of gain matrices, aimed to combine the density, energy, and transverse–longitudinal modulations for a general linear transport line, will be developed in this paper. Inclusion of such cross-plane microbunching structures in semi-analytical Vlasov analysis is a crucial step to systematically characterize phase space modulations for a beamline complex in terms of concatenating individual beamline segments. In this paper we outline the concept of gain matrix and develop a semi-analytical formulation to include the microbunching structures in the aforementioned phase space modulations. Moreover we investigate the phase space microbunching dynamics in an example lattice of the recirculating beamline, compare the semi-analytical calculation with particle tracking simulations, and find that the microbunching amplification calculated from multiplication of concatenated gain matrices can be considered as upper limit to the start-to-end gains.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2026

FFA BEAM TRANSPORT DEMONSTRATION DEVELOPMENT FOR THE CEBAF 22 GeV UPGRADE

Jefferson Lab is planning an upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) to deliver highly polarized electron beams up to 22 GeV using Fixed- Field Alternating-gradient (FFA) magnets. As the application of FFA technology in the 10–22 GeV energy range is unprecedented, experimental validation is required prior to full-scale implementation. To support this effort, a dedicated FFA test insert is proposed within the existing CEBAF infrastructure, with candidate locations in the Beam Switchyard (BSY) dump line or the Hall C beamline. The testbed will consist of a half or full FFA cell using combined-function permanent magnets and will enable systematic studies of beam transport, field quality, alignment, and magnet performance under realistic conditions. Operation with polarized beams in the 5–11 GeV range will closely replicate the energy scaling of the full upgrade. This paper presents the current design status and layout options for the proposed FFA beam transport test line.

Ogur, S. [Thomas Jefferson National Accelerator Fa↗
DOE OSTI2016

Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB

To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Dust particle diffusion in ion beam transport region

Dust particles of μm size produced by a monoplasmatron ion source are observed by a laser light scattering. The scattered light signal from an incident laser at 532 nm wavelength indicates when and where a particle passes through the ion beam transport region. As the result, dusts with the size more than 10 μm are found to be distributed in the center of the ion beam, while dusts with the size less than 10 μm size are distributed along the edge of the ion beam. Floating potential and electron temperature at beam transport region are measured by an electrostatic probe. This observation can be explained by a charge up model of the dust in the plasma boundary region.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Design of PIP-II Medium Energy Beam Transport

The Proton Improvement Plan-II (PIP-II) is a proposed upgrade for the accelerator complex at Fermilab. The central piece of PIP-II is a superconducting radio frequency (SRF) 800 MeV linac capable of operating in both CW and pulse regimes. The PIP-II linac comprises a warm front-end that includes a H⁻ ion source capable of delivering 15-mA, 30-keV DC or pulsed beam, a Low Energy Beam Transport (LEBT), a 162.5 MHz, CW Radio-Frequency Quadrupole (RFQ) accelerating the ions to 2.1 MeV and, a 14-m Medium Energy Beam Transport (MEBT) before beam is injected into SRF part of the linac. This paper presents the PIP-II MEBT design and, discusses operational features and considerations that lead to existing optics design such as bunch by bunch chopping system, minimization of radiation coming to the warm front-end from the SRF linac using a concrete wall, a robust vacuum protection system etc.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Electron stripping processes of H{sup −} ion beam in the 80 kV high voltage extraction column and low energy beam transport line at LANSCE

Basic vacuum calculations were performed for various operating conditions of the Los Alamos National Neutron Science H{sup −} Cockcroft-Walton (CW) injector and the Ion Source Test Stand (ISTS). The vacuum pressure was estimated for both the CW and ISTS at five different points: (1) inside the H{sup −} ion source, (2) in front of the Pierce electrode, (3) at the extraction electrode, (4) at the column electrode, and (5) at the ground electrode. A static vacuum analysis of residual gases and the working hydrogen gas was completed for the normal ion source working regime. Gas density and partial pressure were estimated for the injected hydrogen gas. The attenuation of H{sup −} beam current and generation of electron current in the high voltage acceleration columns and low energy beam transport lines were calculated. The interaction of H{sup −} ions on molecular hydrogen (H{sub 2}) is discussed as a dominant collision process in describing electron stripping rates. These results are used to estimate the observed increase in the ratio of electrons to H{sup −} ion beam in the ISTS beam transport line.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Beam Optics Measurements in Medium Energy Beam Transport at PIP-II Injector Test Facility

The Proton Improvement Plan-II Injector Test (PIP2IT) is an accelerator test facility under construction at Fermilab that will provide a platform to demonstrate critical technologies and concept of the front-end of the PIP-II linear accelerator (linac). The PIP2IT warm front-end comprises a H⁻ ion source capable of delivering 15 mA, 30 keV DC or pulsed beam, a Low Energy Beam Transport (LEBT), a 162.5 MHz, CW Radio Frequency Quadrupole (RFQ) that accelerates the beam to 2.1 MeV and, a 14 m medium energy beam transport (MEBT). Presently, beamline up to the MEBT has been commissioned and operates routinely at the PIP2IT facility. In this paper, we discuss beam measurements performed at the MEBT to analyze beam emittance and its RMS sizes along the MEBT. In addition, beam based calibration of the beamline elements using differential trajectory measurement is also presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Conceptual Design of the Interaction Region Magnets for Future Electron-Ion Collider at Jefferson Lab

The Jefferson Lab Electron Ion Collider (JLEIC) is a proposed new machine for nuclear physics research. As proposed, it will deliver between 15 and 65 GeV center of mass energy collisions between electrons and nuclei. It uses the existing CEBAF accelerator as a full energy injector to deliver 3 to 10 GeV electrons into a new electron collider ring. An all new ion accelerator and collider complex will deliver up to 100 GeV protons, or 40 GeV/nucleon ions. The machine will have luminosity goals of above 1033 cm-2 sec-1 in the whole energy range with a maximum of a few 1034 cm-2 sec-1. The two collider rings use a unique figure-of eight layout to deliver a high degree of polarization in both beams. The machine will include room for two interaction regions with only one initially installed. The crossing angle in the primary interaction region will be 50 mrad. The whole detector region including forward detection covers about 80 meters of the JLEIC complex. This paper will describe the requirements and preliminary designs for both the ion and electron beam magnets in the most complex 32 m long interaction region (IR) around the interaction point (IP). The interaction region has over thirty-seven superconducting magnets operating at 4.5K; these include dipoles, quadrupoles, skew-quadrupoles, solenoids, horizontal and vertical correctors and higher order multipole magnets. The paper will also discuss the electromagnetic interaction between these magnets.

Wiseman, Mark (ORCID:0000000179110306)↗