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NASA NTRS2019

Design Optimization for X-Ray Telescopes

The capability of future X-ray telescopes depends on the quality of their Point Spread Function (PSF) and the size of their field of view. Traditional designs, such as Wolter, and Wolter-Schwarzschild telescopes are stigmatic on the optical axis but their PSF degrades rapidly off-axis. At the optimal focal surface, their PSFs can be significantly improved. We present a simple optimization process for Wolter (W), Wolter-Schwarzschild (WS) and Hyperboloid-Hyperboloid (HH) telescopes that substantially improves the off-axis PSF for either narrow or wide field of view applications. In this paper, we will compare the optical performance of conventional and optimized W-, WS-, and HH-telescopes for a wide range of telescope diameters that can be used to build up future x-ray telescopes.

Saha, Timo T.↗

NASA NTRS2019

Design Optimization for X-ray Telescopes

Timo T Saha↗

NASA NTRS1983

High efficiency spectrographs for the EUV and soft X-rays

The use of grazing incidence optics and reflection grating designs is shown to be a method that improves the performance of spectrographs at wavelengths shorter than 1200 A. Emphasis is laid on spectroscopic designs for X ray and EUV astronomy, with sample designs for an objective reflection grating spectrograph (ORGS) and an echelle spectrograph for wavelengths longer than 100 A. Conical diffraction allows operations at grazing incidence in the echelle spectrograph. In ORGS, the extreme distance of X ray objects aids in collimating the source radiation, which encounters conical diffraction within the instrument, proceeds parallel to the optical axis, and arrives at the detector. A series of gratings is used to achieve the effect. A grazing echelle is employed for EUV observations, and offers a resolution of 20,000 over a 300 A bandpass.

Cash, W.↗

NASA NTRS2019

Development of a Maxwell X-57 High Lift Motor Reference Design

NASA's all-electric X-57 airplane will utilize 14 electric motors, of which 12 are exclusively for lift augmentation during takeoff and landing. This report covers the design and development process taken to create an open reference model representative of the 12 lift augmenting motors. A combined worst case scenario was used as the design point, which represents the simultaneously occurring worst case aspects of thermal, static stress, electromagnetic, and rotor dynamic conditions. This work also highlights the tightly coupled nature of aerospace electric motor design, requiring constant iteration between all disciplines involved. Further adding to the uniqueness is the cooling method, which is limited to nacelle skin forced convection cooling only, no internal air flow is permitted. The stator outer diameter limit of 156.45 mm greatly impacts the degree of coupling between the electromagnetic design with the thermal analysis. The permanent magnet synchronous motor developed here operates between 385 V and 538 V, at a peak current of 50 A. Detailed electromagnetic, thermal, static load, and rotordynamic analysis was completed for this electric motor; all of which are required for a full design. The rotordynamic analysis took into consideration the motor housing which is designed specifically for this motor. The final electric motor has a mass of 2.34 kg, produces 24.1 Nm of torque with a specific power of 5.56 kW/kg, and has an efficiency of 96.61% at the combined worst case design point.

Electric Aircraft↗

DOE OSTI2022

A new class of focusing crystal shapes for Bragg spectroscopy of small, point-like, x-ray sources in laser produced plasmas

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Physics - Plasma physics↗

NASA NTRS2012

Fabrication and Performance of Large Format Transition Edge Sensor Microcalorimeter Arrays

We have produced a variety of superconducting transition edge sensor array designs for microcalorimetric detection of x-rays. Designs include kilopixel scale arrays of relatively small sensors (~75 micron pitch) atop a thick metal heatsinking layer as well as arrays of membrane-isolated devices on 250 micron pitch and smaller arrays of devices up to 600 micron pitch. We discuss the fabrication techniques used for each type of array focusing on unique aspects where processes vary to achieve the particular designs and required device parameters. For example, we evaluate various material combinations in the production of the thick metal heatsinking, including superconducting and normal metal adhesion layers. We also evaluate the impact of added heatsinking on the membrane isolated devices as it relates to basic device parameters. Arrays can be characterized with a time division SQUID multiplexer such that greater than 10 devices from an array can be measured in the same cooldown. Device parameters can be measured simultaneously so that environmental events such as thermal drifts or changes in magnetic fields can be controlled. For some designs, we will evaluate the uniformity of parameters impacting the intrinsic performance of the microcalorimeters under bias in these arrays and assess the level of thermal crosstalk.

Chervenak, James A.↗

NASA NTRS2012

Large Format Transition Edge Sensor Microcalorimeter Arrays

Chervenak, J. A.↗

NASA NTRS2017

Inflatable Antenna for CubeSat: A New Spherical Design for Increased X-Band Gain

Interplanetary CubeSats and small satellites have potential to provide means to explore space and to perform science in a more affordable way. As the goals for these spacecraft become more ambitious in space exploration, the communication systems currently implemented will need to be improved to support those missions. One of the bottlenecks is the antennas’ size, due to the close relation between antenna gain and dimensions. Hence, a possible solution is to develop inflatable antennas which can be packaged efficiently, occupying a small amount of space, and they can provide, once deployed, large dish dimension and correspondent gain. A prototype of a 1 m inflatable antenna for X-Band has been developed in a joint effort between JPL and ASU. After initial photogrammetry tests and radiation tests, it was discovered that the design was not able to meet the required gain. As a result, a new design, based on a spherical inflatable membrane, is proposed. This new design will allow reaching a more stable inflatable surface, hence improving the electromagnetic performance. This paper will detail the principle challenges in developing this new antenna focusing on: design, EM analysis, fabrication and tests.

Babuscia, Alessandra↗

NASA NTRS2000

American X-Vehicles: An Inventory, X-1 to X-45

For a while, it seemed the series of experimental aircraft sponsored by the Air Force and the National Aeronautics and Space Administration had run its course. Between the late 1940s and the late 1970s, almost thirty designations had been allocated to aircraft meant to explore new flight regimes or untried technologies. Then, largely, it ended. But there was a resurgence in the mid- to late-1990s, and as we enter the year 2000 the designations are up to X-45. Many have a misconception that X-Planes have always explored the high-speed and high-altitude flight regimes, something popularized by Chuck Yeager in the original X-1 and the exploits of the twelve men that flew the X-15. Although these flight regimes have always been in the spotlight, many others have been explored by X-Planes. The little Bensen X-25 never exceeded 85 mph, and others were limited to speeds of several hundred mph. There has been some criticism that the use of X designations has been corrupted somewhat by including what are essentially prototypes of future operational aircraft, especially the two JSF demonstrators. But this is not new-the X-11 and X-12 from the 1950s were going to be prototypes of the Atlas intercontinental ballistic missile, and the still-born Lockheed X-27 was always intended as a prototype of a production aircraft. So although this practice does not represent the best use of X designations it is not without precedent. This document is an inventory of the experimental aircraft starting with the X-1 aircraft and ending with the X-45 aircraft.

Miller, Jay↗

NASA NTRS2003

American X-Vehicles: An Inventory X-1 to X-50 Centennial of Flight Edition

For a while, it seemed the series of experimental aircraft sponsored by the U. S. government had run its course. Between the late 1940s and the late 1970s, almost thirty designations had been allocated to aircraft meant to explore new flight regimes or untried technologies. Then, largely, it ended. But there was a resurgence in the mid- to late- 1990s, and as we enter the fourth year of the new millennia, the designations are up to x-50. Many have a misconception that X-vehicles have always explored the high-speed and high-altitude flight regimes - something popularized by Chuck Yeager in the original X-1 and the exploits of the twelve men that flew the X-15. Although these flight regimes have always been in the spotlight, many others have been explored by X-vehicles. The little Bensen X-25 never exceeded 85 mph, and others were limited to speeds of several hundred mph. There has been some criticism that the use of X designations has been corrupted somewhat by including what are essentially prototypes of future operational aircraft, especially the two JSF demonstrators. But this is not new-the X-11 and X-12 from the 1950s were going to be prototypes of the Atlas intercontinental ballistic missile, and the still-born Lockheed X-27 was always intended as a prototype of a production aircraft. So although this practice does not represent the best use of 'X' designations, it is not without precedent.

Jenkins, Dennis R.↗

NASA NTRS1987

Design of low noise, high performance X-ray charge-coupled-device cameras

This paper describes some of the critical details of the MIT X-ray CCD camera design. Special attention is given to those portions of the system that deviate from conventional practice in the design of CCD cameras. Furthermore, an attempt has been made to generalize the design so that both optical and X-ray requirements can be satisfied whenever possible. Currently, noise levels of less than 8 electrons rms are routinely achieved with this design, and even lower levels (less than 5 electrons) should be realizable.

Doty, J. P.↗

DOE OSTI2022

Bayesian optimization to design a novel x-ray shaping device

In radiation therapy, x-ray dose must be precisely sculpted to the tumor, while simultaneously avoiding surrounding organs at risk. This requires modulation of x-ray intensity in space and/or time. Typically, this is achieved using a multi leaf collimator (MLC) - a complex mechatronic device comprising over one hundred individually powered tungsten ‘leaves’ that move in or out of the radiation field as required. Here, an all-electronic x-ray collimation concept with no moving parts is presented, termed “SPHINX”: Scanning Pencil-beam High-speed Intensity-modulated X-ray source. SPHINX utilizes a spatially distributed bremsstrahlung target and collimator array in conjunction with magnetic scanning of a high energy electron beam to generate a plurality of small x-ray “beamlets.” A simulation framework was developed in Topas Monte Carlo incorporating a phase space electron source, transport through user defined magnetic fields, bremsstrahlung x-ray production, transport through a SPHINX collimator, and dose in water. This framework was completely parametric, meaning a simulation could be built and run for any supplied geometric parameters. This functionality was coupled with Bayesian optimization to find the best parameter set based on an objective function which included terms to maximize dose rate for a user defined beamlet width while constraining inter-channel cross talk and electron contamination. Designs for beamlet widths of 5, 7, and 10 mm 2 were generated. Each optimization was run for 300 iterations and took approximately 40 h on a 24-core computer. For the optimized 7-mm model, a simulation of all beamlets in water was carried out including a linear scanning magnet calibration simulation. Finally, a back-of-envelope dose rate formalism was developed and used to estimate dose rate under various conditions. The optimized 5–, 7–, and 10-mm models had beamlet widths of 5.1 , 7.2 , and 10.1 mm 2 and dose rates of 3574, 6351, and 10 015 Gy/C, respectively. The reduction in dose rate for smaller beamlet widths is a result of both increased collimation and source occlusion. For the simulation of all beamlets in water, the scanning magnet calibration reduced the offset between the collimator channels and beam centroids from 2.9 ±1.9 mm to 0.01 ±0.03 mm. A slight reduction in dose rate of approximately 2% per degree of scanning angle was observed. Based on a back-of-envelope dose rate formalism, SPHINX in conjunction with next-generation linear accelerators has the potential to achieve substantially higher dose rates than conventional MLC-based delivery, with delivery of an intensity modulated 100 x 100 mm 2 field achievable in 0.9 to 10.6 s depending on the beamlet widths used. Bayesian optimization was coupled with Monte Carlo modeling to generate SPHINX geometries for various beamlet widths. A complete Monte Carlo simulation for one of these designs was developed, including electron beam transport of all beamlets through scanning magnets, x-ray production and collimation, and dose in water. These results demonstrate that SPHINX is a promising candidate for sculpting radiation dose with no moving parts, and has the potential to vastly improve both the speed and robustness of radiotherapy delivery. A multi-beam SPHINX system may be a candidate for delivering magavoltage FLASH RT in humans.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

NASA NTRS1987

Design of an MSAT-X mobile transceiver and related base and gateway stations

This paper summarizes the results of a design study of the mobile transceiver, base station, and gateway station for NASA's proposed Mobile Satellite Experiment (MSAT-X). Major ground segment system design issues such as frequency stability control, modulation method, linear predictive coding vocoder algorithm, and error control technique are addressed. The modular and flexible transceiver design is described in detail, including the core, RF/IF, modem, vocoder, forward error correction codec, amplitude-companded single sideband, and input/output modules, as well as the flexible interface. Designs for a three-carrier base station and a 10-carrier gateway station are also discussed, including the interface with the controllers and with the public-switched telephone networks at the gateway station. Functional specifications are given for the transceiver, the base station, and the gateway station.

Fang, Russell J. F.↗

NASA NTRS1972

Design of a celestial Thomson-scattering X-ray polarimeter.

A general discussion of the scientific importance and status of stellar X-ray polarimetry is presented. A stellar X-ray polarimeter designed to fit into the bottom half of the NASA OSO-1 wheel compartment or other similar spacecraft is described. In this design, the linear polarization is obtained as a function of energy. The sensitivity of the polarimeter in the 4-24 keV energy range was optimized with the aid of a Monte Carlo simulation computer program and is given for several important celestial X-ray sources. Estimates of sensitivity thresholds for a much larger polarimeter, suitable for flight in the NASA High-Energy Astronomy Observatory (HEAO), are also given. The minimum detectable polarization for several X-ray sources is given.

Landecker, P. B.↗

DOE OSTI2022

X-ray FEL linear accelerator design via start-to-end global optimization

An X-ray Free Electron Laser (FEL) prefers using an electron beam with low emittance, small energy spread, and a high core current to generate coherent radiation through an undulator. In order to attain such a high brightness beam, the linear accelerator beam dynamics design generally involves separate photoinjector optimization and linac optimization. In this paper, we propose a new beam dynamics design strategy based on global optimization with fast start-to-end simulations from the photocathode to the end of the accelerator. The new start-to-end model significantly reduces the simulation time and makes the global optimization practical. The global optimization method avoids the need to choose a single solution based on bunch length at the injector exit for the linac optimization and helps find the solution with unfavorable bunch length at the injector exit but better phase space distribution that can result in better final electron beam phase space distribution at the entrance of the undulator. Here, using the start-to-end global optimization, we showed in an application example, with a 100 pC beam that good transverse emittance and over kilo-Ampere final core current can be attained using a photoinjector that consists of a VHF gun and boosting RF cavities.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

NASA NTRS1993

A review of chemically reactive turbulent flow mixing mechanisms and a new design for a low NO(x) combustor

A review of chemically reactive flow analysis is presented. Key studies are reviewed. The approaches to modeling chemically reactive flows that are discussed are PDF, conserved PDF, conserved scalar, stochastic, and mixing length. Turbulent mixing mechanisms are also discussed and a model is formulated that could be used for optimizing non-premixed gas reacting systems. Consequently, a re-examination of the NO(x) reduction concepts for nonpremixed reactants are suggested together with two new designs for low NO(x) subsonic combustor research.

Mcbeath, Giorgio↗

NASA NTRS1976

Design and fabrication of multigrid X-ray collimators

The paper considers the design and fabrication of multigrid collimators for use in X-ray astronomy. The most important collimator performance criteria are minimum off-band transmission or leakage, and maximum on-band transmission. Lockheed experience with multigrid collimator is summarized: (1) an Oda type with one-dimensional collimation of 1.7 arc minute FWHM and using only the central transmission band, (2) an Oda type with 2 arc minute one-dimensional collimation using up to 27 transmission bands, each separated by 42 arc min. and (3) a modified Parkinson type with two-dimensional collimation of 40 arc sec. Attention is given to grid materials, precision, plating, hole quality, and results of acceptance testing.

Acton, L. W.↗

NASA NTRS2007

Modelling of TES X-ray Microcalorimeters with a Novel Absorber Design

Our development of a novel x-ray absorber design that has enabled the incorporation of high-conductivity electroplated gold into our absorbers has yielded devices that not only have achieved breakthrough performance at 6 keV, but also are extraordinarily well modelled. We have determined device parameters that reproduce complex impedance curves and noise spectra throughout transition. Observed pulse heights, decay time and baseline energy resolution were in good agreement with simulated results using the same parameters. In the presentation, we will show these results in detail and we will also show highlights of the characterization of our gold/bismuth-absorber devices. We will discuss possible improvement of our current devices and expected performance of future devices using the modelling results.

Iyomoto, Naoko↗