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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Effects of ionospheric turbulence on SPS pilot signal

The spatial variation of the electron density was studied by monitoring the differential Doppler on radio beacons aboard the Navy navigation satellites. The radio frequency heater was used to deposit energy in the F-region ionosphere with the heating frequency above peak plasma frequency. The effects of the solar power satellite power beam on the pilot signal were simulated. It was found that a small depletion was formed in the beam and that there was turbulence in the elctron density up the magnetic field line from the beam. It is suggested that the depletion will not seriously affect the power or pilot beams of the solar power satellite.

Clynch, J. R.↗
DOE OSTI2019

Measurement and Analysis of Beam Phase-Space Distributions for the Fermilab Muon Campus Accelerator Complex

The Muon g-2 experiment at Fermilab is tasked with measuring the muon’s anomalous magnetic moment with high precision. Since the experiment requires large amounts of muons, it is imperative to systematically study the behavior of the beam along the transport line. Unfortunately, the available diagnostics only provide beam information in X-Y space. For a complete evaluation, information of the phase-space is required. This paper demonstrates a technique to measure the beam phase-direction distribution by using a set of beam profiles. First, we establish the theoretical framework that describes the principle of the technique. Next, we apply the technique at four different locations along the accelerator delivery line. Finally, we compare our findings to predictions from tracking simulations.

43 PARTICLE ACCELERATORS↗
NASA NTRS2019

Measurements of L-shell X-ray Emission lines of Neonlike Europium on an Electron Beam Ion Trap

We report a measurement of the two X-ray transitions that proceed from the (1s22s22p51∕23d3∕2)J=1 and (1s22s1/22p63p1/2)J =1 upper levels to the (1s22s22p6)J =0 ground level in neonlike Eu53+ (Z = 63), that is, near the previously documented avoided crossing of the two upper levels at Z = 68. The measurement was carried out using the calorimeter spectrometer on the Livermore EBIT-I electron beam ion trap. It affirms the trends set by the neighboring neonlike ions both in terms of the relative intensity of the two lines and in terms of the magnitude of disagreement with theoretical energy level predictions.

Peter Beiersdorfer↗
DOE OSTI2019

Measurements of L-shell X-ray emission lines of neonlike europium on an electron beam ion trap

We report a measurement of the two X–ray transitions that proceed from the (1 s 2 2 s 2 2 p 5 1/2 3 d 3/2 ) J = 1 and (1 s 2 2 s 1/2 2 p 6 3 p 1/2 ) J = 1 upper levels to the (1 s 2 2 s 2 2 p 6 ) J = 0 ground level in neonlike Eu 53+ ( Z = 63), that is, near the previously documented avoided crossing of the two upper levels at Z = 68. The measurement was carried out using the calorimeter spectrometer on the Livermore EBIT–I electron beam ion trap. Here, it affirms the trends set by the neighboring neonlike ions both in terms of the relative intensity of the two lines and in terms of the magnitude of disagreement with theoretical energy level predictions.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2019

Device for controlling additive manufacturing machinery

A computing device for controlling the operation of an additive manufacturing machine comprises a memory element and a processing element. The memory element is configured to store a three-dimensional model of a part to be manufactured, wherein the three-dimensional model defines a plurality of cross sections of the part. The processing element is in communication with the memory element. The processing element is configured to receive the three-dimensional model, determine a path across a surface of each cross section, wherein the path includes a plurality of parallel lines, calculate a power for a radiation beam to scan each of the lines, such that the power varies from line to line non-linearly according to a length of the line, and calculate a scan speed for the radiation beam for each of the lines, such that the scan speed varies line to line non-linearly according to the power of the radiation beam.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Device for controlling additive manufacturing machinery

A computing device for controlling the operation of an additive manufacturing machine comprises a memory element and a processing element. The memory element is configured to store a three-dimensional model of a part to be manufactured, wherein the three-dimensional model defines a plurality of cross sections of the part. The processing element is in communication with the memory element. The processing element is configured to receive the three-dimensional model, determine a path across a surface of each cross section, wherein the path includes a plurality of parallel lines, calculate a power for a radiation beam to scan each of the lines, such that the power varies from line to line non-linearly according to a length of the line, and calculate a scan speed for the radiation beam for each of the lines, such that the scan speed varies line to line non-linearly according to the power of the radiation beam.

Barr, Christian↗
DOE OSTI2013

Application of activity pencil beam algorithm using measured distribution data of positron emitter nuclei for therapeutic SOBP proton beam

Purpose: Recently, much research on imaging the clinical proton-irradiated volume using positron emitter nuclei based on target nuclear fragment reaction has been carried out. The purpose of this study is to develop an activity pencil beam (APB) algorithm for a simulation system for proton-activated positron-emitting imaging in clinical proton therapy using spread-out Bragg peak (SOBP) beams.Methods: The target nuclei of activity distribution calculations are {sup 12}C nuclei, {sup 16}O nuclei, and {sup 40}Ca nuclei, which are the main elements in a human body. Depth activity distributions with SOBP beam irradiations were obtained from the material information of ridge filter (RF) and depth activity distributions of compounds of the three target nuclei measured by BOLPs-RGp (beam ON-LINE PET system mounted on a rotating gantry port) with mono-energetic Bragg peak (MONO) beam irradiations. The calculated data of depth activity distributions with SOBP beam irradiations were sorted in terms of kind of nucleus, energy of proton beam, SOBP width, and thickness of fine degrader (FD), which were verified. The calculated depth activity distributions with SOBP beam irradiations were compared with the measured ones. APB kernels were made from the calculated depth activity distributions with SOBP beam irradiations to construct a simulation system using the APB algorithm for SOBP beams.Results: The depth activity distributions were prepared using the material information of RF and the measured depth activity distributions with MONO beam irradiations for clinical therapy using SOBP beams. With the SOBP width widening, the distal fall-offs of depth activity distributions and the difference from the depth dose distributions were large. The shapes of the calculated depth activity distributions nearly agreed with those of the measured ones upon comparison between the two. The APB kernels of SOBP beams were prepared by making use of the data on depth activity distributions with SOBP beam irradiations that were made from the depth activity distributions with MONO beam irradiations and sorted in terms of energy, SOBP width, and thickness of FD. The data on APB kernels of SOBP beams were determined as installment data for the simulation system using the APB algorithm for SOBP beam irradiations.Conclusions: A method of obtaining the depth activity distributions and the APB algorithm for clinical use of SOBP beams have been developed. It is suggested that the simulation system for imaging the clinical irradiated volume with the APB algorithm can be used in clinical proton therapy using SOBP beams by preparing and investigating the data on APB kernels of SOBP beams.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS1976

Catheter tip force transducer for cardiovascular research

A force transducer for measuring dynamic force activity within the heart of a subject essentially consists of a U-shaped beam of low elastic compliance material. Two lines extend from the beams's legs and a long coil spring is attached to the beam. A strain gauge is coupled to one of the beam's legs to sense deflections thereof. The beam with the tines and most of the spring are surrounded by a flexible tube, defining a catheter, which is insertable into a subject's heart through an appropriate artery. The tines are extractable from the catheter for implantation into the myocardium by pushing on the end of the spring which extends beyond the external end of the catheter.

Feldstein, C.↗
NASA NTRS1989

Coherent Cerenkov radiation from the Spacelab 2 electron beam

The plasma environment of the Spacelab 2 mission was investigated through the deployment of the Plasma Diagnostics Package (PDP) by the Space Shuttle Orbiter and the Orbiter's ejection of a continuous 1-keV/50-mA electron beam along a field line. As the PDP flew by the beam, its plasma-wave instrument detected intense whistler-mode radiation originating from the beam. A detailed model has been developed of the coherent Cerenkov emission process, using a one-dimensional computer simulation of the beam to model the expected phase space structure of the electrons. The power calculated for the modeled 200-m beam segment can easily account for the measured whistler mode wave power.

Farrell, W. M.↗
DOE OSTI2016

SU-F-T-434: Development of a Fan-Beam Optical Scanner Using CMOS Array for Small Field Dosimetry

Purpose: To design and construct a second generation optical computed tomography (OCT) system using a fan-beam with a CMOS array detector for the 3D dosimetry with polymer gel and radiochromic solid dosimeters. The system was specifically designed for the small field dosimetry. Methods: The optical scanner used a fan-beam laser, which was produced from a collimated red laser beam (λ=620 nm) with a 15-degree laser-line generating lens. The fan-beam was sent through an index-matching bath which holds the sample stage and a sample. The emerging laser light was detected with a 2.54 cm-long CMOS array detector (512 elements). The sample stage rotated through the full 360 degree projection angles at 0.9-degree increments. Each projection was normalized to the unirradiated sample at the projection angle to correct for imperfections in the dosimeter. A larger sample could be scanned by using a motorized mirror and linearly translating the CMOS detector. The height of the sample stage was varied for a full 3D scanning. The image acquisition and motor motion was controlled by a computer. The 3D image reconstruction was accomplished by a fan-beam reconstruction algorithm. All the software was developed inhouse with MATLAB. Results: The scanner was used on both PRESAGE and PAGAT gel dosimeters. Irreconcilable refraction errors were seen with PAGAT because the fan beam laser line refracted away from the detector when the field was highly varying in 3D. With PRESAGE, this type of error was not seen. Conclusion: We could acquire tomographic images of dose distributions by the new OCT system with both polymer gel and radiochromic solid dosimeters. Preliminary results showed that the system was more suited for radiochromic solid dosimeters since the radiochromic dosimeters exhibited minimal refraction and scattering errors. We are currently working on improving the image quality by thorough characterization of the OCT system.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2011

Electron density dependence of intensity ratio for FeXXII extreme ultraviolet emission lines arising from different ground levels in electron beam ion trap and large helical device

Extreme ultraviolet (EUV) spectra of highly charged iron ions in a wavelength range of 100-300 A have been observed from two different plasma sources of the Tokyo Electron Beam Ion Trap (Tokyo-EBIT) with a monoenergetic electron beam and a Large Helical Device (LHD) with Maxwellian electron energy. The excitation process of the spectral lines is compared between the two plasmas, and it is found that the excitation process for Fe XIX - Fe XXII ions is clearly different. Namely, the EUV emission lines from the EBIT plasma are only dominated by electron impact excitation connected to the ground state, but the excitation mechanism is not so simple in the LHD plasma. The difference in the excitation process is studied by measuring the intensity ratio of EUV emission lines (114.412 A [1s{sup 2}2s2p{sup 2} {sup 2}P{sub 3/2}{yields}1s{sup 2}2s{sup 2}2p {sup 2}P{sub 3/2}]/117.144 A [1s{sup 2}2s2p{sup 2} {sup 2}P{sub 1/2}{yields}1s{sup 2}2s{sup 2}2p {sup 2}P{sub 1/2}]) arising from different ground levels in the Fe XXII ions. The line intensity ratio has an extremely small value of 0.2 in the EBIT plasma with a low beam current of 30 mA and a beam energy of 2 keV, while the ratio varies with the electron density n{sub e} in the LHD plasmas, i.e., 0.35 for n{sub e} = 1 x 10{sup 13} cm{sup -3} and 0.65 for n{sub e} = 4 x 10{sup 13} cm{sup -3}. Here, the electron density of the EBIT plasma is estimated to be smaller than 10{sup 12} cm{sup -3} and the electron temperature of the LHD plasmas is 2 keV. The dependence of the line intensity ratio on the observed electron density is analyzed for both the EBIT and the LHD plasmas using several collisional-radiative (CR) models. The present experimental data can easily be reproduced by the analysis when the thermal proton impact excitation is taken into account. The importance of the proton impact excitation is also experimentally verified by injecting an iron pellet into the LHD plasmas and changing the ratio of the proton density to the electron density.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2016

Coherent Doppler Lidar for Measuring Velocity and Altitude of Space and Aerial Vehicles

A coherent Doppler lidar has been developed to support future NASA missions to planetary bodies. The lidar transmits three laser beams and measures line-of-sight range and velocity along each beam using a frequency modulated continuous wave (FMCW) technique. Accurate altitude and velocity vector data, derived from the line-of-sight measurements, enables the landing vehicle to precisely navigate from several kilometers above the ground to the designated location and execute a gentle touchdown. The same lidar sensor can also benefit terrestrial applications that cannot rely on GPS or require surface-relative altitude and velocity data.

Amzajerdian, Farzin↗
DOE OSTI2012

FAINT EXTENDED OH EMISSION FROM THE LOCAL INTERSTELLAR MEDIUM IN THE DIRECTION l Almost-Equal-To 108 Degree-Sign , b Almost-Equal-To 5 Degree-Sign

We have mapped faint 1667 OH line emission (T{sub A} Almost-Equal-To 20-40 mK in our Almost-Equal-To 30' beam) along many lines of sight in the Galaxy covering an area of Almost-Equal-To 4 Degree-Sign Multiplication-Sign 4 Degree-Sign in the general direction of l Almost-Equal-To 108 Degree-Sign , b Almost-Equal-To 5 Degree-Sign . The OH emission is widespread, similar in extent to the local H I (r {approx}< 2 kpc) both in space and in velocity. The OH profile amplitudes show a good general correlation with those of H I in spectral channels of Almost-Equal-To 1 km s{sup -1}; this relation is described by T{sub A} (OH) Almost-Equal-To 1.50 Multiplication-Sign 10{sup -4} T{sub B} (H I) for values of T{sub B} (H I) {approx}< 60-70 K. Beyond this the H I line appears to 'saturate', and few values are recorded above Almost-Equal-To 90 K. However, the OH brightness continues to rise, by a further factor Almost-Equal-To 3. The OH velocity profiles show multiple features with widths typically 2-3 km s{sup -1}, but less than 10% of these features are associated with CO(1-0) emission in existing surveys of the area smoothed to comparable resolution.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Characterization of drop aerodynamic fragmentation in the bag and sheet-thinning regimes by crossed-beam, two-view, digital in-line holography

When a spherical liquid drop is subjected to a step change in relative gas velocity, aerodynamic forces lead to drop deformation and possible breakup into a number of secondary fragments. In order to investigate this flow, a digital in-line holography (DIH) diagnostic is proposed which enables rapid quantification of spatial statistics with limited experimental repetition. To overcome the high uncertainty in the depth direction experienced in previous applications of DIH, a crossed-beam, two-view configuration is introduced. With appropriate calibration, this diagnostic is shown to provide accurate quantification of fragment sizes, three-dimensional positions and three-component velocities in a large measurement volume. We apply these capabilities in order to investigate the aerodynamic breakup of drops at two non-dimensional Weber numbers, We, corresponding to the bag (We = 14) and sheet-thinning (We = 55) regimes. Ensemble average results show the evolution of fragment size and velocity statistics during the course of breakup. Our results indicate that mean fragment sizes increase throughout the course of breakup. For the bag breakup case, the evolution of a multi-mode fragment size probability density is observed. This is attributed to separate fragmentation mechanisms for the bag and rim structures. In contrast, for the sheet-thinning case, the fragment size probability density shows only one distinct peak indicating a single fragmentation mechanism. Compared to previous related investigations of this flow, many orders of magnitude more fragments are measured per condition, resulting in a significant improvement in data fidelity. For this reason, this experimental dataset is likely to provide new opportunities for detailed validation of analytic and computational models of this flow.

42 ENGINEERING↗
DOE OSTI2011

A laser-wire beam-energy and beam-profile monitor at the BNL linac

In 2009 a beam-energy monitor was installed in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. This device measures the energies of electrons stripped from the 40mA H{sup -} beam by background gas. Electrons are stripped by the 2.0x10{sup -7}torr residual gas at a rate of {approx}1.5x10{sup -8}/cm. Since beam electrons have the same velocities as beam protons, the beam proton energy is deduced by multiplying the electron energy by m{sub p}/m{sub e}=1836. A 183.6MeV H{sup -} beam produces 100keV electrons. In 2010 we installed an optics plates containing a laser and scanning optics to add beam-profile measurement capability via photodetachment. Our 100mJ/pulse, Q-switched laser neutralizes 70% of the beam during its 10ns pulse. This paper describes the upgrades to the detector and gives profile and energy measurements.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Molecular beam epitaxial growth and scanning tunneling microscopy studies of the gallium rich trench line structure on N-polar w-GaN( 000 1 &#xAF; )

In addition to the usual set of the well-known reconstructions that have been observed on the N-polar GaN surface, namely 1×1, 3×3, 6×6, and c(6×12), an additional structure is occasionally seen at high Ga coverage, which can extend over a large area of the surface. This structure, which is referred to as trench line structure, is partially ordered and consists of parallel-running dark (trench) lines separating wide and narrow strips of atomically ordered regions. There are also randomly placed defects interrupting the ideal ordering. Reflection high energy electron diffraction and scanning tunneling microscopy in ultrahigh vacuum are applied to investigate this trench line structure on samples prepared using molecular beam epitaxy. It is found that the trench line structure results from annealing the Ga-rich c(6×12) at high temperature followed by quenching to room temperature. By careful comparison of the scanning tunneling microscopy images with those from neighboring c(6×12) regions, it is found that the trench line structure can be decomposed into subunits of the c(6×12). Using these subunits, some simple models for the trench line structure are created. It is proposed that the trench line structure is composed of two primary c(6×12) subunits consisting of first and second layer Ga adatoms and that the trench lines are regions devoid of Ga adatoms, going down to the Ga adlayer.

36 MATERIALS SCIENCE↗
DOE OSTI2018

NSLS-II Storage Ring Injection Using a Nonlinear Injection Kicker

The NSLS-II has been operating successfully with top off injection since September 2015. Measurements of the stored beam show a transient of 200 μm in the long straight sections during top off injections. This transient is not desirable for some users, particularly those who specialized in imaging or are otherwise sensitive to beam motion. Users are provided with a signal with which they can gate their detectors, but it is desirable to reduce or eliminate this motion all together. Studies have been performed to reduce the transients, and it is clear that the power supplies require more tunability in the pulse shape in order to reduce the transient across the entire bunch train. Other light sources have explored the possibility of using pulsed quadrupoles and sextupoles as the injection magnet. The stored beam receives no kick as the on-axis fields in these magnets is zero, but the injected beam would see a kick as it is off-center. One drawback of the pulsed quadrupole is that the stored beam experiences a size oscillation. Another issue with a nonlinear kicker is the gradient seen by the injected beam. The transport line needs to be tuned for this gradient, and depending on the strength of the nonlinearity, this gradient may change greatly with injected beam position. Therefore, other facilities have explored other magnet configurations that are nonlinear but have a gradient with less positional dependence. The prospect of using a sextupole kicker was investigated during the design phase of the NSLS-II. It was decided that the idea would not be pursued for several reasons. In particular, the design that was studied the most in depth was not compatible with the standard four bump injection design and the tolerances required were deemed too tight at the time. Other ideas were discussed as well and ultimately none were accepted into the design. In this report we discuss the possibility of placing a nonlinear kicker in the first straight section after the injection straight instead of using the injection bumps. The design of the kicker is based on a design that has been used successfully at BESSY and MAX IV. Our conceptual kicker design is compatible with the existing ring optics and power supply requirements. We show that the transport line is capable of being matched to the required optics. The design does not have restrictive tolerances and is a viable option for a facility upgrade.

36 MATERIALS SCIENCE↗