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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

SU-F-T-210: The Variable Virtual Source-To-Axis Distance Effect On A Compact Proton Pencil Beam Scanning System

Purpose: We investigate the spot characteristic and dose profiles properties from a compact gantry proton therapy system. This compact design features a dedicated pencil beam scanning nozzle with the scanning magnet located upstream of the final 60 degree bending magnet. Due to the unique beam line design, uncertainty has been raised in the virtual source-to-axis distance (SAD). We investigate its potential clinical impact through measurements and simulation. Methods: A scintillator camera based detector was used to measure spot characteristics and position accuracy. An ion chamber array device was used to measure planar dose profile. Dose profile in-air simulation was performed using in-house built MATLAB program based on additional spot parameters directly from measurements. Spot characteristics such as position and in-air sigma values were used to general simulated 2D elliptical Gaussian spots. The virtual SAD distance changes in the longitudinal direction were also simulated. Planar dose profiles were generated by summation of simulated spots at the isocenter, 15 cm above the isocenter, and 15 cm below the isocenter for evaluation of potential clinical dosimetric impact. Results: We found that the virtual SAD varies depending on the spot location on the longitudinal axis. Measurements have shown that the variable SAD changes from 7 to 12 meters from one end to the other end of the treatment field in the longitudinal direction. The simulation shows that the planer dose profiles differences between the fixed SAD and variable SAD are within 3% from the isocenter profile and the lateral penumbras are within 1 mm difference. Conclusion: Our measurements and simulations show that there are minimum effects on the spot characteristics and dose profiles for this up-stream scanning compact system proton system. Further treatment planning study is needed with the variable virtual SAD accounted for in the planning system to show minimum dosimetric impact.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1973

BEAMR: An interactive graphic computer program for design of charged particle beam transport systems

A computer program for a PDP-15 is presented which calculates, to first order, the characteristics of charged-particle beam as it is transported through a sequence of focusing and bending magnets. The maximum dimensions of the beam envelope normal to the transport system axis are continuously plotted on an oscilloscope as a function of distance along the axis. Provision is made to iterate the calculation by changing the types of magnets, their positions, and their field strengths. The program is especially useful for transport system design studies because of the ease and rapidity of altering parameters from panel switches. A typical calculation for a system with eight elements is completed in less than 10 seconds. An IBM 7094 version containing more-detailed printed output but no oscilloscope display is also presented.

Leonard, R. F.↗
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 OSTI2016

SU-G-TeP1-10: Predicting Photon Percentage Depth Dose From Profile Due to Changes in Beam Quality

Purpose: To predict photon percentage depth dose (PDD) from profile due to a change in flattened (FF) and flattening-filter-free (FFF) beam quality. Methods: 6MV photon beam PDDs and profiles in a 3D water tank (3DW) and profiles in an ionization chamber array (ICP) were collected for different field sizes and depths with FF and FFF beams in a Versa HD (Elekta Ltd.). The energy was adjusted by changing the bending magnet current (BMC) ±15% from the clinical beam (6MV) in 5% increments. For baseline establishment, PDDs(depth≥3cm) were parameterized with bi-exponential functions and the PDD 20 to 10cm ratios (PDD{sub 20,10}) were calculated. Then, the FF profile at 10cm from the central axis (Pr{sub 10}) and the slope of the FFF central linear region (SFFF) were calculated. Calibration curves were established: (1) change in Pr{sub 10} and SFFF as functions of the change in PDD{sub 20,10} and (2) change in PDD(depth=3, 15 and 30cm) as function of the change in PDD{sub 20,10}. The differences between Pr{sub 10} and SFFF from baseline were calculated and, from calibration curves, changes in PDD{sub 20,10} and PDD(depth=3, 15 and 30cm) were obtained. Then, absolute PDD(depth=3, 15 and 30cm) values were input into a least-square-optimization algorithm to calculate the bi-exponential function’s optimal coefficients and generate the PDD(depths≥3cm). Results: The change in PDD{sub 20,10} relative to baseline increased (<±4%) with BMC. Pr{sub 10} increased (±6%) and SFFF decreased (±11%) with BMC. Relative differences between measured and calculated (i.e. PDD calculation from Pr{sub 10} and SFFF) PDDs were less than 1%. Results apply to FF and FFF beams measured in 3DW and ICP. Conclusion: Pr{sub 10} and SFFF are more sensitive than PDD to changes in beam energy and PDD information can be accurately generated from them. With known 3DW and ICP profile relationship, ICP can be used to obtain PDD for current photon beam.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2019

Permanent Magnet Dipole-Quadrupole and Correcto-Tuner for Small Bore Accelerators

Electromagnets are used to bend electron beams and generate X-ray light. Permanent magnets have many advantages over electromagnets and are being studied as an alternative for small bore accelerators. This paper focuses on the mechanical design of two holders. First, a holder for the corrector and tuner permanent magnet assembly, which aims to correct the errors in the permanent magnetic field strength and orientation. Second, a holder for the dipole-quadrupole magnet assembly, which aims to provide the required magnetic strength to steer the electrons. Prototypes for the corrector, tuner and dipole-quadrupole holders were designed and tested to validate conceptual design. Results show that the corrector magnets can be oriented into a prescribed configuration, the tuner magnets can be oriented simultaneously regardless of the magnetic forces involved, and the dipole-quadrupole magnets can provide the magnetic strength required to steer electrons.

Huschke, Christopher↗
DOE OSTI2019

1D Transient Study of Glidcop Surface Heating by Beam Power

Radiation fans from Insertion Devices and Bending Magnets are “trimmed” by various water-cooled absorbers located strategically downstream of those sources. Mostly, the absorber surfaces onto which power is deposited is constructed from Glidcop (rarely OFHC copper). A ring-resident Active Interlock (AI) system is designed to protect against overheating by disabling mis-steered beam within an allotted time. The Synchrotron Radiation Protection (SRP) protocol has the limiting criterion of 100*C maximum allowable temperature at any point when subject to mis-steered beam for a fixed period before the AI takes action. After 0.2 msec, radiation in excess of the +/- 500 um offset and +/- 250 urad angular error from the HEX SCW will trip in fault. AI specified beam parameters allow 1.0 msec to fully dump the electron beam. Given such short periods of peak power deposition we explore here these brief thermal transients to glean a general understanding of highest reachable limits before the onset of AI protection.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Projection x-ray topography system at 1-BM x-ray optics test beamline at the advanced photon source

Projection X-ray topography of single crystals is a classic technique for the evaluation of intrinsic crystal quality of large crystals. In this technique a crystal sample and an area detector (e.g., X-ray film) collecting intensity of a chosen crystallographic reflection are translated simultaneously across an X-ray beam collimated in the diffraction scattering plane (e.g., [1, 2]). A bending magnet beamline of a third-generation synchrotron source delivering x-ray beam with a large horizontal divergence, and therefore, a large horizontal beam size at a crystal sample position offers an opportunity to obtain X-ray topographs of large crystalline samples (e.g., 6-inch wafers) in just a few exposures. Here we report projection X-ray topography system implemented recently at 1-BM beamline of the Advanced Photon Source. A selected X-ray topograph of a 6-inch wafer of 4H-SiC illustrates capabilities and limitations of the technique.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

APS: High-Energy X-rays Expediting Applied and Fundamental Research

The Advanced Photon Source (APS) at Argonne National Laboratory (ANL) was designed and built as one of the first large 3rd generation synchrotrons operated at 7 GeV. The United States Department of Energy (DOE) Office of Science funded the construction and continues to fund the operation of this national facility. Furthermore, the beamlines were originally operated by Collaborative Access Teams (CAT), which allowed a strong involvement of research institutes, universities, and industry. Today 43 of 68 beamlines are operated by the X-ray Science Division (XSD) and 35 beamlines are directly funded by the DOE Office of Science. The APS became operational in 1995, and was planned right from the beginning with 4 beamlines dedicated to high-energy x-rays above 40 keV: 1-ID designed to study engineering materials science, 6-ID-D for magnetism and condensed matter research, 11-ID-B dedicated to magnetic Compton scattering using an Elliptical Multipole Wiggler, and 11-ID-C for materials science and condensed matter physics. These stations were later joined by the bending magnet beamlines 6-BM for white beam studies and 17-BM for rapid powder diffraction. CAT operated beamlines such as 15-ID for crystallography or 16-ID for high-pressure studies also use the high-energy x-ray regime frequently. The program in Compton scattering ended in 2004 and the wiggler was replaced by an undulator. 11-ID-B became the first dedicated station for Pair Distribution Function (PDF) Analysis.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

From Spreadsheet to Assembly, Using NX Automation

At Thomas Jefferson National Accelerator Facility (JLab), accelerator physicists design beamlines that will accelerate electrons to energies up to 12 GeV. Beamline designs are created, employing a series of SRF accelerating cavities, bending and focusing electro-magnets, and beam diagnostics. Typically, mechanical and structural constraints are not taken into consideration in the initial designs and this results in many design iterations. A typical beamline will have hundreds to thousands of design components listed in their design orbit. Previously, components needed to be inserted one at a time to populate the beamline assembly. A process was developed at JLab to take accelerator physics data and automate the process to populate an assembly with the thousands of components. A spreadsheet of position and orientation data as well as a component matrix of part names vs. Teamcenter elements are input files for customized a NX journaling program, which is used to place the many elements into the resulting assembly. This presentation explains the process, the challenges, and the tools used to develop this process and the resulting project. An examination of the time savings is also presented.

Lassiter, Ronald↗
NASA NTRS1996

Investigation of ion-beam machining methods for replicated x-ray optics

The final figuring step in the fabrication of an optical component involves imparting a specified contour onto the surface. This can be expensive and time consuming step. The recent development of ion beam figuring provides a method for performing the figuring process with advantages over standard mechanical methods. Ion figuring has proven effective in figuring large optical components. The process of ion beam figuring removes material by transferring kinetic energy from impinging neutral particles. The process utilizes a Kaufman type ion source, where a plasma is generated in a discharge chamber by controlled electric potentials. Charged grids extract and accelerate ions from the chamber. The accelerated ions form a directional beam. A neutralizer outside the accelerator grids supplies electrons to the positive ion beam. It is necessary to neutralize the beam to prevent charging workpieces and to avoid bending the beam with extraneous electro-magnetic fields. When the directed beam strikes the workpiece, material sputters in a predicable manner. The amount and distribution of material sputtered is a function of the energy of the beam, material of the component, distance from the workpiece, and angle of incidence of the beam. The figuring method described here assumes a constant beam removal, so that the process can be represented by a convolution operation. A fixed beam energy maintains a constant sputtering rate. This temporally and spatially stable beam is held perpendicular to the workpiece at a fixed distance. For non-constant removal, corrections would be required to model the process as a convolution operation. Specific figures (contours) are achieved by rastering the beam over the workpiece at varying velocities. A unique deconvolution is performed, using series-derivative solution developed for the system, to determine these velocities.

Drueding, Thomas W.↗
NASA NTRS2001

Fabricating and using a micromachined magnetostatic relay or switch

A micromachined magnetostatic relay or switch includes a springing beam on which a magnetic actuation plate is formed. The springing beam also includes an electrically conductive contact. In the presence of a magnetic field, the magnetic material causes the springing beam to bend, moving the electrically conductive contact either toward or away from another contact, and thus creating either an electrical short-circuit or an electrical open-circuit. The switch is fabricated from silicon substrates and is particularly useful in forming a MEMs commutation and control circuit for a miniaturized DC motor.

Tai, Yu-Chong↗
DOE OSTI2018

High Radiation Environment Nuclear Fragment Separator Magnet (Final Report)

Dipole magnets with a field of 2 T are needed for the 30° bend in the Facility for Rare Isotope Beams (FRIB) fragment separator. This magnet will be subjected to extremely high radiation and heat loads from the high radiation. Superconducting coils for this magnet would allow low power operation but traditional NbTi and Nb3Sn superconductors are sensitive to quenches from beam loss and must operate near 4.5 K where the removal of thermal heat generated by beam loss is inefficient due to basic Carnot principles. High Temperature Superconductor (HTS) offers a unique solution for the magnets in the high radiation environment expected at FRIB. These conductors can operate at 40 K where heat removal is an order of magnitude more efficient than at 4.5 K. The curved separator dipoles subtend a large angular bend which introduces some complications in the winding of the coils. One approach would be to wind the coils with a curved section on the inner and outer radial segments (banana shaped). The inner radial segment would be wound with a negative curvature that would tend to unwind. An alternate approach would be to use a straight segment on the inner segment to avoid the negative curvature (D-shaped). In Phase I coils with a limited number of turns were successfully wound for both configurations described. These coils were tested at 77 K in liquid nitrogen. The Phase II program concentrated on the design, structural analysis, prototyping and test of the HTS curved dipole coils required for the high radiation environment of the FRIB fragment separator region. A thermal analysis was performed to simulate that the heat load can be removed. A test coil containing 500 m of HTS conductor was constructed to be tested at the 40 K operating temperature. The anticipated heat load was simulated with heater strips to demonstrate that the heat can be removed and that the coil can operate in a stable state.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2026

Development of combined function dipole-quadrupole PMQs magnets for NSLS-II upgrade

This paper focuses on the R&D performed for the development of permanent magnets-based dipoles-quadrupoles combined function magnets (PMQs) for the future NSLSII upgrade “complex bend” lattice (CB). This new lattice uses PMQs that provide both bending (dipole) and strong focusing (quadrupole) magnetic field on the electron beam. The permanent magnet (PM) technology is suitable for the high magnetic field strengths (0.5 T, 130 T/m) required for such combine function magnets. PM technology leads to a compact magnet design that is essential in realizing the complex bend lattice concept, as well as a passive magnet solution which does not require electrical power supply reducing power consumption by ~ 80% (from 1.7 MW to 0.3 MW for NSLS-II). Two PMQs magnets designs are under consideration: A hybrid design that use both PM and soft iron poles, and Halbach type that is a pure PM design. Both PMQs designs present challenges in achieving the specified magnetic field quality due to their higher sensitivity to errors (mechanical tolerances and PM properties). This paper presents cost-effective designs and prototypes results for hybrid and Halbach PMQs, addressing various technical challenges while meeting the field requirements of the complex bend lattice for the NSLS-II upgrade.

N'gotta, Patrick [Brookhaven]↗
DOE OSTI2017

Instrument design optimization with computational methods

Using Finite Element Analysis to approximate the solution of differential equations, two different instruments in experimental Hall C at the Thomas Jefferson National Accelerator Facility are analyzed. The time dependence of density uctuations from the liquid hydrogen (LH2) target used in the Q wea k experiment (2011-2012) are studied with Computational Fluid Dynamics (CFD) and the simulation results compared to data from the experiment. The 2.5 kW liquid hydrogen target was the highest power LH2 target in the world and the first to be designed with CFD at Jefferson Lab. The first complete magnetic field simulation of the Super High Momentum Spectrometer (SHMS) is presented with a focus on primary electron beam deflection downstream of the target. The SHMS consists of a superconducting horizontal bending magnet (HB) and three superconducting quadrupole magnets. The HB allows particles scattered at an angle of 5:5 deg to the beam line to be steered into the quadrupole magnets which make up the optics of the spectrometer. Without mitigation, remnant fields from the SHMS may steer the unscattered beam outside of the acceptable envelope on the beam dump and limit beam operations at small scattering angles. A solution is proposed using optimal placement of a minimal amount of shielding iron around the beam line.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Magnetic Field Mapping of a 2.5 T Fixed-Field HTS Gantry Magnet for Proton Therapy

We present results from testing a high-temperature superconducting (HTS) magnet prototype for proton therapy. This magnet is specifically designed for a novel rotating gantry capable of delivering the entire proton beam energy range (70225 MeV) while maintaining a fixed magnetic field in the superconducting magnets. The gantry layout simplifies the magnet design, enabling the use of straight, flat racetrack Bi-2223 (DI-BSCCO) coil technology and operation at higher temperatures (1015 K). The magnet has a non-linear field distribution for bending and focusing the proton beams. To validate this feature, we developed a system for measuring the magnetic field distribution in the magnet aperture. We present the design of this hall probe array and experimental results from two different magnet tests at 4.2 K in a liquid helium bath. These results are compared with the simulated field distribution and discussed in the context of the required field quality for the application.

Mosat, M↗
DOE OSTI2018

Reasonable Beam Deviation Envelope for Ray-tracing

At NSLS-II the unused dipole radiation is intercepted by the photon absorbers installed inside the vacuum chamber. The water-cooled absorbers are designed to take away the heat therefore the temperature is kept within the safety limit. However, if the beam orbit is severely perturbed, the radiation fan could pass through the geometry and strikes on the vacuum chamber components. This ray-leakage is a possible reason of the accelerator component temperature rise observed during the high-current operations. The goal of this work is to find the maximum beam deviation at the dipole hence ray-tracing can be re-examined under the operational constraints. The beam is confined to the orbit by the bending and focusing magnets. At NSLS-II the orbit is further controlled by a real time orbit feedback loop. Beam could be lost in any unpredictable direction if the magnet malfunctions. Consequently reasonable assumptions must be made to define the deviation envelope. It was determined that the dipole radiation is not powerful enough to cause damage within 10 ms, for example, if the rf power is shut off and the beam deviates from the orbit. Therefore we consider the radiation produced by the stored beam only; temporarily processes, such as unstable oscillating beam, should not be a concern. The orbit of the stored beam can be altered during magnet failures. The dipole current is interlocked to a small range of ±2% from the nominal value. If the dipole current changes slowly the beam energy automatically adjusts and the orbit remains the same. If the dipole current changes rapidly the beam will not be stable. Therefore dipole variation need not to be considered. For the other magnets we consider one magnet failure at a time because it is unlikely that two fail at the same time. It was found that the beam lifetime drops dramatically if one quadrupole power supply is turned off; therefore this scenario does not meet the stable beam condition. The current of one quadrupole could drop but will not result in orbit change with the feedback on. Beam could survive if one sextupole power supply is turned off, but the orbit will not be changed. Magnet could partially fail, for example, one or part of the coil shorts due to break-down. This is a low probability event and will not be considered. During daily operations the orbit is changed by the correctors and the rf frequency. In this work the correctors and the rf frequency are varied to explore the deviation envelope.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Bent Bragg–Laue monochromator for high-energy X-rays

A bent Bragg–Laue monochromator (BLM) is proposed for high-energy X-ray (~25–60 keV) beamlines. The BLM has the unique feature of bi-directional focusing. A sagittally bent Laue crystal can focus the large horizontal fan of a bending magnet or wiggler source. A meridionally bent Bragg crystal focuses the beam vertically and corrects for the anticlastic bending effects of the Laue crystal. This monochromator geometry relies on the crystal orientations being optimized. We show that the focusing condition and Rowland condition can be simultaneously satisfied at a given energy. A detailed ray tracings indicate that a BLM can provide similar energy resolution and higher flux density compared to a sagittally bent double-Laue monochromator configuration. A prototype BLM with a symmetric Bragg crystal and an asymmetric Laue crystal was tested. Matching of the bend radii of the two crystals in the meridional direction was demonstrated. Generally, the horizontal acceptance of the sagittally bent Laue crystal is limited by the large curvature. This horizontal BLM acceptance could be increased by translating the Laue crystal along its sagittal bending axis.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1991

Stabilization of large space structures by linear reluctance actuators

Application of magnetic forces are considered for stabilization of vibrations of flexible space structures. Three electromagnetic phenomena are studied, such as: (1) magnetic body force; (2) reluctance torque; and (3) magnetostriction, and their application is analyzed for stabilization of a beam. The magnetic body force actuator uses the force that exists between poles of magnets. The reluctance actuator is configured in such a way that the reluctance of the magnetic circuit will be minimum when the beam is straight. Any bending of the beam increases the reluctance and hence generates a restoring torque that reduces bending. The gain of the actuator is controlled by varying the magnetizing current. Since the energy density of a magnetic device is much higher compared to piezoelectric or thermal actuators, it is expected that the reluctance actuator will be more effective in controlling the structural vibrations.

Biswas, Saroj K.↗