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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

DARHT Axis 1 Bremsstrahlung Dose Measurements

he Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility provides flash radiography ca pabilities using two electron Linear Induction Accelerators (LIA’s). Axis-1 of DARHT produces, nominally, a 20-MeV, 1.5-kA, 80-ns-Full Width at Half Max (FWHM) electron beam. The elec tron beam is focused on to a tantalum target to produce a Bremsstrahlung x-ray dose for flash radiography of dynamic systems. This paper will describe and compare a variety of techniques for determining the x-ray dose for two different beam currents produced by a 55mm and 70mm diameter cathode. The data was taken in November of 2022 on DARHT Axis 1. The experimen tal measurement techniques include a platinum calorimeter, a diamond radiation detector (DRD), and a Compton diode (CD). Gafchromic EBT3 self-developing dosimetry film was also used, but no useful results were obtained. Beam charge and energy were recorded and dose was calculated with this information using xtr with Dosecalcx, and simple dose charge-energy scaling. In this pa per, we will discuss the target geometry and experimental layout, the methods of measuring dose, dose diagnostics and measurement of beam charge and energy, and the comparisons of data and calculations.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Cathode to Target Simulations for Scorpius: I. Simulation Codes and Models

The new Scorpius linear induction electron accelerator is under development for multi-pulse flash radiography of large, explosively-driven hydrodynamic experiments. Beam physics from the cathode to the target was examined with computer simulations, including envelope, ray-trace, and particle-in cell (PIC) codes. Beam instabilities investigated included beam breakup (BBU), image displacement, diocotron, parametric envelope, ion hose, and the resistive wall instability. Beam corkscrew motion and emittance growth from beam mismatch were also studied. The results of these simulations is documented in a series of reports. In this report the computer codes and physical models used for these simulations are described. The conclusion of this study is that Scorpius will produce and accelerate a beam with radiographic quality equivalent to the present accelerators at Los Alamos National Laboratory if the same engineering standards and construction details are upheld.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

2D Simulations of Diamagnetic Loop Calibrations

Diamagnetic loops can be used as a non-invasive method for measurements of beam size in electron beam accelerators that use solenoidal magnetic transport. A comprehensive theory for interpreting data from a diamagnetic loop relates the rms beam radius to the excluded flux measured by the loop and the beam current. Thus, primary calibration of the loop must relate the loop signal directly to the exclude d flux. We have simulated these calibrations with a 2D field solver in order to identify possible sources of uncertainty in our calibration technique.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Diamagnetic Loop Testing on DARHT-I

Diamagnetic loops (DML) can be used as a noninvasive method for measurements of beam size in electron beam accelerators that use solenoidal magnetic transport. The loop fundamentally measures the magnetic flux excluded by a diamagnetic object. A comprehensive theory relates the rms beam radius to the excluded flux measured by the DML. We have built, and calibrated a DML apparatus. Recently, this DML has been used to measure the size of the electron beam near the final focus of the DARHT-I flash-radiography accelerator. Results are in agreement with beam transport code predictions. In this article, we review and summarize the construction, calibration, and electron-beam testing of this DML.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Unwrapping Radiograph Target Disassembly Using Adaptive Machine Learning [Slides]

Advanced analysis methods were developed to determine the electron temperature and density evolution of targets disassembly by intense electron beams at DARHT based on shearing interferometer and shadowgraph measurements. New methods have been developed to spatially and temporally resolve electron velocity and temperature, expanding on recently published first results of Aluminum target disassembly. A surrogate model has been created for use in developing Adaptive Machine Learning analysis techniques. The results will also be used to guide the development of the system and experimental approach to future measurements on DARHT Axis-I and a new system to be deployed on DARHT Axis-II.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

LIA Performance Limitations

Location: SLAC National Accelerator Laboratory Presenter: Evan R Scott Date: 29 August 2023 Purpose: Part of SDRD for collaboration with SLAC

SDRD, SLAC, linear induction accelerator, cathode,↗
DOE OSTI2023

Reflections

Flash radiography is a much used diagnostic technique for high-explosively driven hydrodynamic experiments. Two linear-induction electron accelerators (LIAs) at the Los Alamos Dual Axis Radiography of Hydrodynamic Tests (DARHT) facility provide the source spots for point projection radiography of exceptionally large and dense experiments. In these LIAs, the beam acceleration is provided by high-voltage pulses applied to a number of inductively isolated gaps. The high-voltage pulses are produced by remotely located pulsedpower generators and delivered to the gaps by long highvoltage cables. For Scorpius, these pulse generators are called line replacement units (LRUs).

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Magnetically Levitated and Constrained Flywheel Energy Storage System

The concept of using linear induction motors to lift, constrain, accelerate, and decelerate a large-scale flywheel is proposed, and some of the advantages are investigated. Calculations for a Magnetically Levitated Energy Storage System (MLES) are performed that compare a single large scale MLES with a current state of the art flywheel energy storage system in order to show the relative differences and advantages of such a system. The system that is used for comparison is a typical Beacon Power flywheel energy system. This is currently one of the state-of-the-art flywheel energy storage systems and so it can be used to provide a basic data set to compare to an MLES system.

VanOsdol, John↗
NASA NTRS1992

Knolle Magnetrans: A magnetically levitated train system

The Knolle Magnetrans is a continuous transportation system featuring small cars traveling in rapid succession, levitated by permanent magnets in repulsion, and propelled by stationary linear induction motors. The vehicles' headway, speed, acceleration, and deceleration are designed into the system and mechanically enforced. Passengers board dynamically and controls consist of a simple on-off relay. This paper summarizes the system design goals, describes the system components and discusses related environmental issues.

Knolle, Ernst G.↗
NASA NTRS1983

Effect of the amount of Na2SO4 on the high temperature corrosion of Udimet-700

The corrosion of Udimet-700, coated with different doses of Na2SO4, was studied in an isothermal thermogravimetric test in the temperature range 900 to 950 C. The weight gain curve is characterized by five distinct stages: an initial period of linear corrosion; an induction period; a period of accelerated corrosion; a period of decelerating corrosion; and a period of parabolic oxidation. The time required for the failure of the alloy increases with an increase in the amount of Na2SO4, reaches a peak and then decreases with further increase in the amount of Na2SO4. For low and intermediate doses (0.3 to 2.0 mg/sq cm), the catastrophic failure of the material occurs by the formation of Na2MoO4 and interaction of the liquid Na2MoO4 with the alloy. For heavy doses, the degradation of the material is due to the formation of large amounts of sulfides.

Misra, A. K.↗
NASA NTRS1990

Superconducting six-axis accelerometer

A new superconducting accelerometer, capable of measuring both linear and angular accelerations, is under development at the University of Maryland. A single superconducting proof mass is magnetically levitated against gravity or any other proof force. Its relative positions and orientations with respect to the platform are monitored by six superconducting inductance bridges sharing a single amplifier, called the Superconducting Quantum Interference Device (SQUID). The six degrees of freedom, the three linear acceleration components and the three angular acceleration components, of the platform are measured simultaneously. In order to improve the linearity and the dynamic range of the instrument, the demodulated outputs of the SQUID are fed back to appropriate levitation coils so that the proof mass remains at the null position for all six inductance bridges. The expected intrinsic noise of the instrument is 4 x 10(exp -12)m s(exp -2) Hz(exp -1/2) for linear acceleration and 3 x 10(exp -11) rad s(exp -2) Hz(exp -1/2) for angular acceleration in 1-g environment. In 0-g, the linear acceleration sensitivity of the superconducting accelerometer could be improved by two orders of magnitude. The design and the operating principle of a laboratory prototype of the new instrument is discussed.

Paik, H. J.↗
DOE OSTI2021

Load dynamics of double planar foil liners and double planar wire arrays on the UM MAIZE LTD generator

In previous studies using the University of Nevada, Reno's (UNR's) high-impedance Zebra Marx generator (1.9 Ω, 1.7 MA, 100 ns), Double Planar Wire Arrays (DPWAs) proved to be excellent radiators, and Double Planar Foil Liners (DPFLs) proved useful for future inertial confinement fusion applications. This article presents the results of joint UNR/UM (University of Michigan) experiments with aluminum (Al) DPWAs, Al DPFLs, and tungsten (W) DPWAs using UM's Michigan Accelerator for Inductive Z-Pinch Experiments (MAIZE) generator, a low-impedance Linear Transformer Driver (LTD) (0.1 Ω, 0.5–1 MA, and 100–250 ns). The main goals of this study were twofold: the first was a pioneering effort to test whether a relatively heavy Al DPFL could successfully be imploded on a low-impedance university-scale LTD like the MAIZE generator, and, if so, to analyze the results and make comparisons to the optimized, lighter DPWA configurations that have been previously studied. The DPWAs consisted of two planes of micrometer-scale diameter Al or W wires, while the DPFLs consisted of two planes of micrometer-scale thickness Al foils. Diagnostics include filtered Si-diodes, an absolutely calibrated filtered PCD, x-ray pinhole cameras, spectrometers, and gated optical self-emission imaging. The implosion dynamics and radiative properties of Al DPWAs and DPFLs and W DPWAs on the MAIZE LTD are discussed and compared. Time-dependent load inductance calculations derived from measurements of the load current and a MAIZE circuit model provide a relative measurement of pinch strength. In experiments on MAIZE, W planar wire arrays exhibited a higher peak load inductance throughout the pinch than Al DPWAs and DPFLs, while x-ray pulses from Al DPFLs had the longest emission duration.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1981

Recent developments in mass drivers

In the past eight months a new mass driver concept has been explored through calculation and inductance model verification. It retains the linear synchronous principle and freedom from arcs, plasmas or physical contact between the accelerated bucket and accelerator. However, it discards passive magnetic flight and obtains transverse focussing from strong off-axis restoring forces produced by drive coils operating in a pull-only mode. This paper gives the reasoning on which the new concept is based, and applies the concept to a lunar catapult design.

Oneill, G. K.↗
NASA NTRS1989

Radiation effects in Caenorhabditis elegans - Mutagenesis by high and low LET ionizing radiation

The nematode C. elegans was used to measure the effectiveness of high-energy ionized particles in the induction of three types of genetic lesions. Recessive lethal mutations in a 40-map unit autosomal region, sterility, and X-chromosome nondisjunction or damage were investigated. Induction rates were measured as a function of linear energy transfer, LET(infinity), for nine ions of atomic nunmber 1-57 accelerated at the BEVALAC accelerator. Linear kinetics were observed for all three types of lesions within the dose/fluence ranges tested and were found to vary strongly as a function of particle LET(infinity). Relative biological effectiveness (RBE) values of up to 4.2 were measured, and action cross sections were calculated and compared to mutagenic responses in other systems.

Nelson, Gregory A.↗
NASA NTRS1996

Cellular and molecular analysis of mutagenesis induced by charged particles of defined linear energy transfer

Mutation induction by charged particles of defined linear energy transfer (LET) and gamma rays was scored using human-hamster hybrid AL cells. The LET values for charged particles accelerated at the Radiological Research Accelerator Facility ranged from 10 keV/microm protons to 150 keV/microm 4He ions. The induced mutant fractions at both the S1 and HGPRT loci were dependent on the dose and LET. In addition, for each dose examined, the mutant yield at the S1 locus was 30-60 fold higher than at the corresponding HGPRT locus. To determine whether the mutation spectrum was comparably dependent on dose and LET, independent S1- and HGPRT- mutants induced by 150 keV/microm 4He ions and gamma rays were isolated, and their DNA was analyzed by both Southern blotting and multiplex PCR methods. While the majority of radiation-induced mutants showed deletions of varying sizes, the relative percentage of large deletions was found to be related to both the dose and LET of the radiation examined. Using a mutation system that can detect multilocus changes, results of the present study show that radiation-induced chromosomal loss can be in the millions of base pairs.

NASA Discipline Radiation Health↗