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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Studies of space-charge-dominated multispecies beam in a solenoid based beam transport line

A self-consistent particle-in-cell (PIC) simulation is used to study the transport properties of a space-charge-dominated multispecies beam propagating through a solenoid-based low energy beam transport line. The evolution of the beam radius and emittance growth of each species arising due to the nonlinear space-charge forces has been investigated. The self-consistent PIC simulation shows the formation of hollow density profiles of subdominant unwanted species around the primary beam, downstream of the transport line. We have utilized this effect for efficient removal of unwanted species by making use of a slit at a suitable location in the beam line.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Phase Trombone Design in the Beam Transfer line for the Project PIP-II at Fermilab

PIP-II beam transfer line (BTL) to transport the beam from PIP-II Linac to the Booster ring at Fermilab. One crucial aspect of the BTL design involved the implementation of collimators. These collimators play a vital role in removing large amplitude particles from the beamline that might otherwise miss the horizontal and vertical edge of the foil at the point of the Booster injection. To ensure the effectiveness of these collimators, simulation was conducted to determine their optical placement within the BTL. The simulation revealed that the precise control of accumulated phase advances between the collimators and the foil was crucial. To achieve this control, a phase trombone is needed within the BTL. The phase trombone serves as an adjustment mechanism, allowing for the fine-tuning of the phase advance between the collimators and the foil, thus optimizing the performance of the collimation process. This paper discusses and presents the details of the design and implementation of the phase trombone within the PIP-II BTL.

43 PARTICLE ACCELERATORS↗
DOE OSTI2013

Effect of subdominant species on the evolution of intense primary beam in a low energy beam transport line

The dynamics of space-charge-dominated multispecies beam with different distributions has been studied in a solenoid based low energy beam transport line using a particle-in-cell simulation method. Results are presented in wide parameter regimes covering emittance dominated as well as space charge dominated multispecies beams consisting of p, H{sub 2}{sup +}, and H{sub 3}{sup +} beams. Simulation shows the formation of hollow distribution of H{sub 2}{sup +} and H{sub 3}{sup +} beams around the desired proton beam and separation is more distinct as the fraction of proton is increased. The hollow formation is almost independent of combination of H{sub 2}{sup +} and H{sub 3}{sup +} beams, once the fraction of proton beam is fixed. The emittance growth of proton is found to increase sharply in the space-charge-dominated regime and is more in the cases where proton fraction is low.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

TH-A-19A-10: Fast Four Dimensional Monte Carlo Dose Computations for Proton Therapy of Lung Cancer

Purpose: To develop and validate a fast and accurate four dimensional (4D) Monte Carlo (MC) dose computation system for proton therapy of lung cancer and other thoracic and abdominal malignancies in which the delivered dose distributions can be affected by respiratory motion of the patient. Methods: A 4D computer tomography (CT) scan for a lung cancer patient treated with protons in our clinic was used to create a time dependent patient model using our in-house, MCNPX-based Monte Carlo system (“MC{sup 2}”). The beam line configurations for two passively scattered proton beams used in the actual treatment were extracted from the clinical treatment plan and a set of input files was created automatically using MC{sup 2}. A full MC simulation of the beam line was computed using MCNPX and a set of phase space files for each beam was collected at the distal surface of the range compensator. The particles from these phase space files were transported through the 10 voxelized patient models corresponding to the 10 phases of the breathing cycle in the 4DCT, using MCNPX and an accelerated (fast) MC code called “FDC”, developed by us and which is based on the track repeating algorithm. The accuracy of the fast algorithm was assessed by comparing the two time dependent dose distributions. Results: The error of less than 1% in 100% of the voxels in all phases of the breathing cycle was achieved using this method with a speedup of more than 1000 times. Conclusion: The proposed method, which uses full MC to simulate the beam line and the accelerated MC code FDC for the time consuming particle transport inside the complex, time dependent, geometry of the patient shows excellent accuracy together with an extraordinary speed.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

High intensity proton injector for facility of antiproton and ion research

The high current ion source with the low energy beam transport (LEBT) will serve as injector into the proton LINAC to provide primary proton beam for the production of antiprotons. The pulsed ion source developed and built in CEA/Saclay operates with a frequency of 2.45 GHz based on ECR plasma production with two coils with 87.5 mT magnetic field necessary for the electron cyclotron resonance. The compact LEBT consists of two solenoids with a maximum magnetic field of 500 mT including two integrated magnetic steerers to adjust the horizontal and vertical beam positions. The total length of the compact LEBT is 2.3 m and was made as short as possible to reduced emittance growth along the beam line. To measure ion beam intensity behind the pentode extraction system, between solenoids and at the end of the beam line, two current transformers and a Faraday cup are installed. To get information about the beam quality and position, the diagnostic chamber with different equipment will be installed between the two solenoids. This article reports the current status of the proton injector for the facility of antiproton and ion research.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Operation of the intensity monitors in beam transport lines at Fermilab during Run II¹

The intensity of charged particle beams at Fermilab must be kept within pre-determined safety and operational envelopes in part by assuring all beam within a few percent has been transported from any source to destination. Beam instensity monitors with toroidial pickups provide such beam intensity measurements in the transport lines between accelerators at FNAL. With Run II, much effort was made to continually improve the resolution and accuracy of the system.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Space-charge compensation measurements in electron cyclotron resonance ion source low energy beam transport lines with a retarding field analyzer

In this paper we describe the first systematic measurement of beam neutralization (space charge compensation) in the ECR low energy transport line with a retarding field analyzer, which can be used to measure the potential of the beam. Expected trends for the space charge compensation levels such as increase with residual gas pressure, beam current, and beam density could be observed. However, the overall levels of neutralization are consistently low (<60%). The results and the processes involved for neutralizing ion beams are discussed for conditions typical for ECR injector beam lines. The results are compared to a simple theoretical beam plasma model as well as simulations.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

GIXRD measurements at EDXRD beamline at INDUS-2 synchrotron

The energy dispersive x-ray diffraction (EDXRD) beam line at beam port no. BL-11, INDUS-2, RRCAT (Indore) has been adapted for grazing incidence x-ray diffraction (GIXRD) measurements in both out-of plane and in-plane geometry. With the help of energy sensitive high resolution HPGe detector, we have been able to record diffraction data from thin films of thicknesses ranging from few nanometers to hundreds of nanometers. We are presenting here a few demonstrative examples to illustrate the capabilities and possible implications of EDXRD beamline in carrying out structural investigations of thin films.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

What have we learned from the LCLS injector?

The LCLS injector reliably delivered a high quality electron beam since it started operations three years ago. Some initial commissioning results were described in Ref. [1]. This note is to summarize what we have understood from the LCLS injector including drive laser, cathode, RF gun, injector beam line elements, beam modeling and operations. What we have learned during the LCLS injector commissioning and operation has lead to modified specifications for the UV drive laser system. A flat temporal profile originally required in the LCLS design is not necessary to achieve a low emittance electron beam for the LCLS operations. According to our recent studies, a laser pulse with 3 ps Gaussian temporal profile (FWHM) can achieve a similar emittance compared to a flat temporal profile laser. The sensitivity of the emittance to the laser pulse length at 250 pC of bunch charge was studied, as shown in Figure 1. Only slight variations were observed for both projected and time-sliced emittances with laser pulses from 2.2 ps to 4.5 ps FWHM. Space charge forces certainly become weak but RF emittance which is proportional to the bunch length square increases due to the longer laser pulse. Thus, the projected emittance optimum may be a trade-off between space charge forces and RF emittance, while the time-sliced emittance determined by space charge forces may be slightly improved with a longer laser pulse length. Simulations and theory also show that spatial Gaussian-cut laser profile produces a better emittance compared to uniform profiles due to increased linearity of the space charge forces. Preliminary experimental data show that the emittance with a Gaussian-cut is almost as good as the one with uniform although not better than. In addition, the laser transmission through the iris for spatial Gaussian-cut is about twice the one for spatial uniform. More experimental studies with the new Coherent laser system are needed to make a more solid conclusion.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

A RHIC-style IPM in the Brookhaven AGS

Beam profiles in the two storage rings of the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Lab (BNL) are measured with ionization profile monitors (IPMs). Each ring has a vertical and horizontal detector. An IPM measures the distribution of electrons produced in the beam line by beam ionization of background gas. These detectors have been developed at BNL in a program that began in 1996. The current detectors are a design that was based on a prototype built in 2007 and used in RHIC from 2007 to 2012. During the 2012 shutdown we refurbished this prototype and installed it into the Alternating-Gradient Synchrotron (AGS). This paper describes the new AGS IPM and shows data from the detector commissioning.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

The FFAG return loop for the CBETA Energy Recovery Linac

The CBETA energy recovery linac uses a single xed eld alternating gradient (FFAG) beam line to return the beam for electron beams with four energies, ranging from 42 MeV to 150 MeV. To keep the beam line compact, the ends of the return line have a small radius of curvature, but the central part of the return line is straight. These are connected by transition lines that adiabatically change from one to the other. We rst describe the design or the arc cell. We then describe how a straight cell is created to be a good match to this arc cell. We then describe the design of the transition line between them. The design process makes use of eld maps for the desired magnets. Because we switch magnet types as we move from the arc, through the transition, and into the straight, there are discrete jumps in the elds that degrade the adiabaticity of the transition, and we describe corrections to manage that.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

CONCEPT OF A POLARIZED POSITRON SOURCE FOR CEBAF

Positron beams would provide new and meaningful probes for the experimental program at the Thomas Jefferson National Accelerator Facility (JLab), including but not limited to future hadronic physics and dark matter experiments. Critical requirements involve generating positron beams with a high degree of spin polarization, sufficient intensity and a continuous-wave (CW) bunch train compatible with acceleration to 12 GeV at the Continuous Electron Beam Accelerator Facility (CEBAF). To address these requirements, a polarized positron injector based upon the bremsstrahlung of an intense CW spin polarized electron beam is considered*. First a polarized electron beam line provides >1 mA of polarized electrons at ~120 MeV to a high-power target for positron production. Next, a second beam line collects, shapes and aligns the spin of positrons for users. Finally, the positron beam is matched into the CEBAF acceptance for acceleration and transport to the end stations with energies up to 12 GeV. An optimized layout to provide positrons beams with intensity >100 nA (polarized) or intensity >3 µA (unpolarized) will be discussed in this poster.

Habet, S. H.↗
DOE OSTI2015

Overview of the Neutron Radiography and Computed Tomography at the Oak Ridge National Laboratory and Applications

The Oak Ridge National Laboratory (ORNL) Neutron Sciences Directorate (NScD) has installed a neutron imaging (NI) beam line at the High Flux Isotope Reactor (HFIR) cold guide hall. The CG-1D beam line produces cold neutrons for a broad range of user research spanning from engineering to material research, additive manufacturing, vehicle technologies, archaeology, biology, and plant physiology. Recent efforts have focused on increasing flux and spatial resolution. A series of selected engineering applications is presented here. Historically and for more than four decades, neutron imaging (NI) facilities have been installed exclusively at continuous (i.e. reactor-based) neutron sources rather than at pulsed sources. This is mainly due to (1) the limited number of accelerator-based facilities and therefore the fierce competition for beam lines with neutron scattering instruments, (2) the limited flux available at accelerator-based neutron sources and finally, (3) the lack of high efficiency imaging detector technology capable of time-stamping pulsed neutrons with sufficient time resolution. Recently completed high flux pulsed proton-driven neutron sources such as the ORNL Spallation Neutron Source (SNS) at ORNL and the Japanese Spallation Neutron Source (JSNS) of the Japan Proton Accelerator Research Complex (J-PARC) in Japan produce high neutron fluxes that offer new and unique opportunities for NI techniques. Pulsed-based neutron imaging facilities RADEN and IMAT are currently being built at J-PARC and the Rutherford National Laboratory in the U.K., respectively. ORNL is building a pulsed neutron imaging beam line called VENUS to respond to the U.S. based scientific community. A team composed of engineers, scientists and designers has developed a conceptual design of the future VENUS imaging instrument at the SNS.

additive manufacturing↗
DOE OSTI2011

Measuring the 2{gamma} Exchange Effect in Electron-Proton Scattering at CLAS

Recent results from experiments at Jefferson Laboratory, Newport News VA, which measure the ratio of the electric to magnetic form factors of the proton, G{sub E}/G{sub M}, have forced us to reexamine the single photon exchange approximation in lepton-proton elastic scattering. Discrepancies between the ratio obtained via the time-tested Rosenbluth separation method and new polarization transfer measurements, which differ by as much as a factor of three, may be resolved by considering the effect of two photon exchange (TPE). Theoretical corrections for the TPE effect are difficult due to the large number of excited nucleon states that can contribute to the process. The TPE effect can, however, be determined directly by measuring the ratio of the positron-proton to electron-proton elastic scattering cross sections, R = {sigma}(e{sup +})/{sigma}(e{sup -}), since the TPE effect changes sign with the charge of the incident particle. The CLAS TPE experiment at Jefferson Laboratory, will determine the effect of two-photon exchange in elastic lepton-proton scattering by precisely measuring the ratio of positron-proton to electron-proton elastic cross sections over a large kinematic range (0.1<{epsilon}<0.96, 0.02{<=}Q{sup 2}{<=}2.0). We will accomplish this by directing the 5.5 GeV primary electron beam, provided by the Continuous Electron Beam Accelerator Facility (CEBAF), onto a set of radiators and converters to produce simultaneous and identical beams of electron and positrons. Acceptance and efficiency concerns are minimized by only considering the ratios of the elastic cross sections and switching polarity of magnets in the beam line and the spectrometer. Guided by the results of a short 2006 test run and extensive GEANT based modeling, new shielding and beam line components were designed to maximize luminosity. The unique experimental design and challenges of the TPE experiment and the projected luminosities will be presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Start-to-end beam dynamics simulation of double triangular current profile generation in Argonne Wakefield Accelerator

Double triangular current profile (DT) gives a high transformer ratio which is the determining factor of the performance of collinear wakefield accelerator. This current profile can be generated using the emittance exchange (EEX) beam line. Argonne Wakefield Accelerator (AWA) facility plans to generate DT using the EEX beam line. We conducted start-to-end simulation for the AWA beam line using PARMELA code. Also, we discuss requirements of beam parameters for the generation of DT.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

The design of the new IR beamline at ASTRID2

We report on the successful design, installation and commission of the new AU-IR beam line at ASTRID2. ASTRID2 is the new synchrotron facility running at top-up mode and at 580 MeV, which is optimized for low energies at Aarhus University, Denmark. The highlight of the beam line is that it is simple, low cost and reliable. The optics system consists of two gold-coated mirrors only and is as close as 1.367 m away from an entrance edge of a bending magnet. This allows a horizontal acceptance angle of 35 mrad and a vertical acceptance of 28 mrad. The source point is chosen to be near the leading edge of the bending magnet where the electron beam enters the dipole field. This allows us to use the strong edge radiation from the bending magnet together with the bending radiation. The beam line is equipped with a Vertex{sup TM} 70v FTIR spectrometer from Bruker{sup TM}. The beam line design and choice of the “rock-solid” optical design version of spectrometer ensure a good reliability to beam drift and vibrations. Currently, the system is running at mid-range IR. Further upgrades have been planned.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Radiation Safety Consideration for the Parasitic Final Focus Test Beam at SLAC

A low intensity electron beam parasitic to the operation of the Stanford Linear Collider (SLC) has been transported through the Final Focus Test Beam (FFTB) facility making secondary test beams available for users. Photons generated in collimation of the SLC electron and positron beams in the linac pass through a splitter magnet that deflects the primary beams away from the linac axis into the SLC beam lines. These photons are converted to electrons and positrons in a secondary production target located down beam on the hnac axis. The secondary electrons are then transported through the FFTB beam line onto experimental detectors. The average power of the parasitic beam is very low, thus, it presents no hazards. However, various accident scenarios involving failure of the splitter magnet and the active protection devices could send much more powerful SLC beams (up to 90 kilo-watts) into this zero-degree secondary beam line. For the accident case, the average power in the transmitted beam was calculated using the Monte Carlo programs EGS4 and TURTLE. Results from analysis of the radiation protection systems that assure safety during the parasitic operation are presented.

Rokni, S. H.↗