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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Strong field physics and QED experiments with ELI-NP 2×10PW laser beams

The ELI-NP facility will focus a 10 PW pulsed laser beam at intensities of ∼10{sup 23} W/cm{sup 2} for the first time, enabling investigation of the new physical phenomena at the interfaces of plasma, nuclear and particle physics. The electric field in the laser focus has a maximum value of ∼10{sup 15} V/m at such laser intensities. In the ELI-NP Experimental Area E6, we propose the study of Radiation Reaction, Strong Field Quantum Electrodynamics (QED) effects and resulting production of Ultra-bright Sources of Gamma-rays which could be used for nuclear activation. Two powerful, synchronized 10 PW laser beams will be focused in the E6 Interaction Chamber on either gas or solid targets. One 10 PW beam is the Pump-beam and the other is the Probe-beam. The focused Pump beam accelerates the electrons to relativistic energies. The accelerated electron bunches interact with the very high electro-magnetic field of the focused Probe beam. The layout of the experimental area E6 will be presented with several options for the experimental configurations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Simulation of periodically focused, adiabatic thermal beams

Self-consistent particle-in-cell simulations are performed to verify earlier theoretical predictions of adiabatic thermal beams in a periodic solenoidal magnetic focusing field [K.R. Samokhvalova, J. Zhou and C. Chen, Phys. Plasma 14, 103102 (2007); J. Zhou, K.R. Samokhvalova and C. Chen, Phys. Plasma 15, 023102 (2008)]. In particular, results are obtained for adiabatic thermal beams that do not rotate in the Larmor frame. For such beams, the theoretical predictions of the rms beam envelope, the conservations of the rms thermal emittances, the adiabatic equation of state, and the Debye length are verified in the simulations. Furthermore, the adiabatic thermal beam is found be stable in the parameter regime where the simulations are performed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Belle II Detector: status and proposed US contributions

Conference proceedings for the 2012 American Physical Society, Division of Particles and Fields (DPF2012) conference. Paper is on the US contibutions to the Belle II detector upgrade. High precision flavor physics measurements are an essential complement to the direct searches for new physics at the LHC. Such measurements will be performed using the upgraded Belle II detector and upgraded KEKB accelerator. The status of the Belle II detector and proposed role of the US Belle II collaborators are presented in this article. The B factory experiments, Belle at the KEKB collider at KEK and BaBar at the PEP II collider at SLAC, were built to measure the large mixing-induced CP violation in the B0 system predicted by the theory of Kobayashi and Maskawa. The successful confirmation of the prediction led to the Nobel Prize for both theorists. The B factories were built to answer the question Is the CKM description in the Standard Model correct? Most B factory results are in good agreement with the expectations from the Standard Model (SM) and confirm the CKM structure of quark mixing and CP violation, but some measurements show tensions with the SM prediction. The Super B factories will address the question In what way is the Standard Model wrong? Much larger datasets are needed for high-precision measurements to search for significant deviations from the SM which are expected to exist. The SuperKEKB and Belle II detector are being constructed to perform these high precision studies with a dataset 50ab{sup -1}. The SuperKEKB accelerator will operate at an instantaneous luminosity of 8 x 10{sup 35}cm{sup -2}s{sup -1}, a factor of 40 times higher than the luminosity of the KEKB accelerator at the end of the Belle physics program. The increased luminosity will derive primarily from shrinking the beam size at the interaction point (nano beams) utilizing new final focus quadrapole magnets in combination with a factor of 2 increase in beam currents. To counteract the increase in the beam-beam parameter due to the reduced beta functions, the beam emittance must also be reduced; this will be achieved with a new electron source and a new damping ring.

43 PARTICLE ACCELERATORS↗
DOE OSTI2013

Ion source and beam guiding studies for an API neutron generator

Recently developed neutron imaging methods require high neutron yields for fast imaging times and small beam widths for good imaging resolution. For ion sources with low current density to be viable for these types of imaging methods, large extraction apertures and beam focusing must be used. We present recent work on the optimization of a Penning-type ion source for neutron generator applications. Two multi-cusp magnet configurations have been tested and are shown to increase the extracted ion current density over operation without multi-cusp magnetic fields. The use of multi-cusp magnetic confinement and gold electrode surfaces have resulted in increased ion current density, up to 2.2 mA/cm{sup 2}. Passive beam focusing using tapered dielectric capillaries has been explored due to its potential for beam compression without the cost and complexity issues associated with active focusing elements. Initial results from first experiments indicate the possibility of beam compression. Further work is required to evaluate the viability of such focusing methods for associated particle imaging (API) systems.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Numerical study of a bucked-coil system for muon transport and cooling

A Neutrino Factory, which can deliver an intense flux of {approx}10{sup 21} neutrinos per year from a multi-GeV stored muon-beam is seemingly the ideal tool for studying neutrino oscillations and CP-violations for leptons. The front-end of this facility plays a critical role in determining the number of muons that can be accepted by the downstream accelerators. Delivering peak performance requires transporting the muon beams through long sections of a beam channel containing high-gradient rf cavities and strong focusing solenoids. Here, we propose a novel scheme to improve the performance of the cavities, thereby increasing the number of muons within the acceptance of the accelerator chain. The key element of our new scheme is to apply a set of bucked coils along the lattice, thus forcing the external magnetic field to drop substantially within the cavity. We incorporate this idea into a new lattice design for a Neutrino Factory, and detail its performance numerically.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Transport characteristics of a Glaser magnet for an axisymmetric and non-axisymmetric space charge dominated beam

This paper describes the dynamics of space charge dominated beam through a Glaser magnet which is often used to focus charged particle beams in the low energy section of accelerators and in many other devices. Various beam optical properties of the magnet and emittance evolution that results from the coupling between the two transverse planes are studied. We have derived ten independent first order differential equations for the beam sigma matrix elements assuming the linear space-charge force consistent with the assumption of the canonically transformed KV like distribution. In addition, the feasibility of using a Glaser magnet doublet in a low energy beam injection line to match an initial non-axisymmetric high intensity beam with net angular momentum to an axisymmetric system to suppress effective emittance growth after transition back to an uncoupled system, has also been studied.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Shielding of the azimuthal magnetic field by the anode plasma in a relativistic self-magnetic-pinch diode

In relativistic electron beam diodes, the self-generated magnetic field causes electron-beam focusing at the center of the anode. Generally, plasma is formed all over the anode surface during and after the process of the beam focusing. In this work, we use visible-light Zeeman-effect spectroscopy for the determination of the magnetic field in the anode plasma in the Sandia 10 MV, 200 kA (RITS-6) electron beam diode. The magnetic field is determined from the Zeeman-dominated shapes of the Al III 4 s –4 p and C IV 3 s –3 p doublet emissions from various radial positions. Near the anode surface, due to the high plasma density, the spectral line-shapes are Stark-dominated, and only an upper limit of the magnetic field can be determined. The line-shape analysis also yields the plasma density. The data yield quantitatively the magnetic-field shielding in the plasma. In conclusion, the magnetic-field distribution in the plasma is compared to the field-diffusion prediction and found to be consistent with the Spitzer resistivity, estimated using the electron temperature and charge-state distribution determined from line intensity ratios.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Scanning systems for particle cancer therapy

A particle beam to treat malignant tissue is delivered to a patient by a gantry. The gantry includes a plurality of small magnets sequentially arranged along a beam tube to transfer the particle beam with strong focusing and a small dispersion function, whereby a beam size is very small, allowing for the small magnet size. Magnets arranged along the beam tube uses combined function magnets where the magnetic field is a combination of a bending dipole field with a focusing or defocusing quadrupole field. A triplet set of combined function magnets defines the beam size at the patient. A scanning system of magnets arranged along the beam tube after the bending system delivers the particle beam in a direction normal to the patient, to minimize healthy skin and tissue exposure to the particle beam.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Light focusing using epsilon-near-zero metamaterials

We present a strategy of focusing light using epsilon-near-zero metamaterials with embedded dielectric cylinder. The focusing mechanism is analytically investigated, and its accuracy is substantiated by rigorous full-wave simulations. It is found that the focusing intensity is highly depend on the embedded medium and its size, and the magnetic field amplitude of the focused beam itself can reach as high as 98.2 times the incident field. Owing to its versatility, the proposed light focusing system is sure to find applications in fields such as bio-sensing and in nonlinear optics.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Commissioning the Super High Momentum Spectrometer in Hall C at Jefferson Lab

The Super High Momentum Spectrometer (SHMS) is a new spectrometer installed in Hall C at Jefferson Lab that can detect particles over a range of central momenta from 2-11 GeV/c and scattering angles from 5.5 to 40 degrees. Jefferson Lab delivers a high intensity electron beam with an energy up to 11 GeV to fixed targets in Hall C. The SHMS is a highly precise and essential upgrade for the 12 GeV Jefferson Lab physics program. Its beam line consists of a dipole magnet with a 3-degree horizontal bend, three quadrupole magnets for horizontal and vertical focusing of the beam, and the spectrometer dipole capable of a 4 T central magnetic field and 18.4-degree bend angle. Measurements in Hall C can be taken with the SHMS independently or in coincidence with the existing High Momentum Spectrometer (HMS). The SHMS was installed in the spring of 2017 and commissioned during the fall 2017/winter 2018 using a range of electron beam energies. This talk summarizes the initial results of the optics tuning of the SHMS and the performance during recent experimental running to include initial elastic hydrogen scattering measurements.

Szumila-Vance, Holly↗
DOE OSTI2023

Chirality reversal of magnetic solitons in chiral Cr 1/3 TaS 2

Ferromagnetism in two-dimensional (2D) materials provides an ideal platform to study emergent electromagnetic phenomena in low dimensions for future spintronics. In magnetic-element intercalated transition metal dichalcogenides, topologically nontrivial spin textures, such as chiral helimagnetic spin states and chiral soliton lattices, are realized due to the chiral lattice distortions induced by intercalated magnetic ions. Consequently, the magnetic chirality is predictably determined by the sign of antisymmetric exchange interaction (or Dzyaloshinskii–Moriya interaction, DMI) vector that is coupled to the underlying crystal chirality. Here, using cryogenic Lorentz phase microscopy, we directly observed the chirality reversal behavior of the chiral soliton lattices in Cr 1/3 TaS 2 across the structural defects. We show that a partial 1 T stacking in 2H-TaS 2 locally reduces DMI, leading to magnetic chirality reversal with direct atomic resolution imaging. Furthermore, our experimental results show that manipulation of stacking sequence provides a viable way to control the chirality of topologically nontrivial soliton lattices in 2D magnets.

2D materials↗
DOE OSTI2014

Focusing electrode and coaxial reflector used for reducing the guiding magnetic field of the Ku-band foilless transit-time oscillator

Based on the theoretical analysis of the intense relativistic electron beam propagation in the coaxial drift-tube, a focusing electrode and a coaxial reflector is proposed to lessen the demand of the coaxial Ku-band foilless transit-time oscillator (TTO) for the guiding magnetic field. Moreover, a Ku-band TTO with the focusing electrode and the coaxial reflector is designed and studied by particle in cell simulation. When the diode voltage is 390 kV, the beam current 7.8 kA, and the guiding magnetic field is only 0.3 T, the device can output 820 MW microwave pulse at 14.25 GHz by means of the simulation. However, for the device without them, the output power is only 320 MW. The primary experiments are also carried out. When the guiding magnetic field is 0.3 T, the output power of the device with the focusing electrode and the coaxial reflector is double that of the one without them. The simulation and experimental results prove that the focusing electrode and the coaxial reflector are effective on reducing the guiding magnetic field of the device.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Resistive Wall Simulations for the DARHT Multi-Pulse Test Line

The multi-pulse test line (MPTL) presently under T development at the Dual Axis Radiography Hydrodynamic Test (DARHT) facility may have several meters of drifting beam transport without external magnetic focusing field. The absence of external magnetic focusing is the worst case for growth of the resistive-wall instability. This instability is usually considered to be strictly a long-pulse (low-frequency) problem, but has been theoretically shown to couple the multiple pulses in a long pulse train, such as are expected to be the subject of experimentation on the MPTL. In this note, we explore the resistive wall instability in the MPTL parameter range using our LAMDA beam dynamics code. (LAMDA stands for Linear Accelerator Model for DARHT)

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Space Charge Correction on Emittance Measurement of Low Energy Electron Beams

The goal of any particle accelerator is to optimize the transport of a charged particle beam along a set path by confining the beam to a small region close to the design trajectory and directing it accurately along the beamline. To do so in the simplest fashion, accelerators use a system of magnets that exert approximately linear electromagnetic forces on the charged beam. These electromagnets bend the beam along the desired path, in the case of bending magnets, and constrain the beam to the desired area through alternating focusing and defocusing effects, in the case of quadrupole magnets. We can model the transport of such a beam through transfer matrices representing the actions of the various beamline elements. However, space charge effects, produced from self electric fields within the beam, defocus the beam and must be accounted for in the calculation of beam emittance. We present below the preliminary results of a MATLAB code built to model the transport of a charged particle beam through an accelerator and measure the emittance under the influence of space charge effects. We demonstrate the method of correctly calculating the emittance of a beam under space charge effects using a least square fit to determine the initial properties of the beam given the beam size measured at a specific point after transport.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Foil focusing of relativistic electron beams

When an intense relativistic electron beams (IREB) passes through a grounded metal foil, the transverse electric field due to the beam space charge is locally shorted out, and the beam is focused by the magnetic field of its current. The effect can be treated as focusing by a thin lens with first order aberration. Expressions for the focal length and aberration coefficient of the equivalent thin lens are developed in this note. These are then applied to practical examples representative of IREB research at Los Alamos National Laboratory.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Muon Beam Emittance Evolution in the Helical Ionization Cooling Channel for Bright Muon Sources

The six-dimensional ionization cooling is essential to design a bright muon source. A geometry constraint is a challenge issue in a compact helical cooling channel (HCC). Especially, the HCC requires a large bore helical magnet and a compact helical RF system to incorporate the RF into the magnet chamber. A new emittance evolution has been designed to mitigate the geometry constraint. The HCC was functionally separated into three parts sections. The lattice at the initial section provides a large transverse acceptance by using a strong helical focus magnet. Once the transverse beam size is small enough to get into the compact RF the HCC lattice in the middle section generates a large longitudinal beta tune to dominate the longitudinal cooling. Consequently, the longitudinal emittance becomes smaller than the transverse one at the end of middle section. In the final section, the magnetic field strength is gradually reduced to match out the helical channel to the straight solenoid. As a result, the emittance exchange takes place and the final transverse emittance becomes smaller than the longitudinal one. The new emittance evolution scenario will be discussed in this presentation.

Derbenev, Yaroslav↗