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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 1,333 records · Page 74
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Z-Slicer: A Scheme for Shaping the Electron Beam Profile in a Linac

A train of short bunches ( 100 fs) are at a premium at accelerator facilities and their applications include terahertz (THz) generation, short bunch diagnostics, advanced accelerator R&D, etc. In this work we report on the design and simulation of an experiment involving a 20 MeV electron beam, that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through unaffected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, or transverse deflecting cavity. The tuning variable is only the RF-chirp. The detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

RHIC polarized proton-proton operation at 100 GeV in Run 15

The first part of RHIC Run 15 consisted of ten weeks of polarized proton on proton collisions at a beam energy of 100 GeV at two interaction points. In this paper we discuss several of the upgrades to the collider complex that allowed for improved performance. The largest effort consisted in commissioning of the electron lenses, one in each ring, which are designed to compensate one of the two beam-beam interactions experienced by the proton bunches. The e-lenses raise the per bunch intensity at which luminosity becomes beam-beam limited. A new lattice was designed to create the phase advances necessary for a beam-beam compensation with the e-lens, which also has an improved off-momentum dynamic aperture relative to previous runs. In order to take advantage of the new, higher intensity limit without suffering intensity driven emittance deterioration, other features were commissioned including a continuous transverse bunch-by-bunch damper in RHIC and a double harmonic RF cature scheme in the Booster. Other high intensity protections include improvements to the abort system and the installation of masks to intercept beam lost due to abort kicker pre-fires.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Method for passively compensating for temperature coefficient of gain in silicon photomultipliers and similar devices

A method for designing a completely passive bias compensation circuit to stabilize the gain of multiple pixel avalanche photo detector devices. The method includes determining circuitry design and component values to achieve a desired precision of gain stability. The method can be used with any temperature sensitive device with a nominally linear coefficient of voltage dependent parameter that must be stabilized. The circuitry design includes a negative temperature coefficient resistor in thermal contact with the photomultiplier device to provide a varying resistance and a second fixed resistor to form a voltage divider that can be chosen to set the desired slope and intercept for the characteristic with a specific voltage source value. The addition of a third resistor to the divider network provides a solution set for a set of SiPM devices that requires only a single stabilized voltage source value.

47 OTHER INSTRUMENTATION↗
DOE OSTI2015

Absorber for terahertz radiation management

A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Plume collimation for laser ablation electrospray ionization mass spectrometry

In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

47 OTHER INSTRUMENTATION↗
DOE OSTI2015

TRIO: Burst Buffer Based I/O Orchestration

The growing computing power on leadership HPC systems is often accompanied by ever-escalating failure rates. Checkpointing is a common defensive mechanism used by scientific applications for failure recovery. However, directly writing the large and bursty checkpointing dataset to parallel filesystem can incur significant I/O contention on storage servers. Such contention in turn degrades the raw bandwidth utilization of storage servers and prolongs the average job I/O time of concurrent applications. Recently burst buffer has been proposed as an intermediate layer to absorb the bursty I/O traffic from compute nodes to storage backend. But an I/O orchestration mechanism is still desired to efficiently move checkpointing data from bursty buffers to storage backend. In this paper, we propose a burst buffer based I/O orchestration framework, named TRIO, to intercept and reshape the bursty writes for better sequential write traffic to storage severs. Meanwhile, TRIO coordinates the flushing orders among concurrent burst buffers to alleviate the contention on storage server bandwidth. Our experimental results reveal that TRIO can deliver 30.5% higher bandwidth and reduce the average job I/O time by 37% on average for data-intensive applications in various checkpointing scenarios.

Wang, Teng↗
DOE OSTI2014

Superconducting Cavity Cryomodule Designs for the Next Generation of CW Linacs: Challenges and Options

The designs of nearly all superconducting RF (SRF) linacs over the last several years, with one notable exception being CEBAF at Jefferson Lab, have assumed pulsed beam operation with relatively low duty factors. These include the XFEL at DESY, the ILC, the original configuration for Project X at Fermilab, as well as several others. Recently proposed projects, on the other hand, including the LCLS-II at SLAC, the newly configured low and medium energy sections for Project X, and FRIB at Michigan State, to name a few, assume continuous wave or CW operation on quite a large scale with ambitious gradients and cavity performance requirements. This has implications in the cavity design as well as in many parts of the overall cryomodule due to higher dynamic heat loads in the cavities themselves and higher heat loads in the input and high-order-mode (HOM) couplers. Piping internal to the cryomodule, the effectiveness of thermal intercepts, the size of integrated heat exchangers, and many other aspects of the overall design are also affected. This paper will describe some of these design considerations as we move toward the next generation of accelerator projects.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

First Steps Toward Incorporating Image Based Diagnostics Into Particle Accelerator Control Systems Using Convolutional Neural Networks

At present, a variety of image-based diagnostics are used in particle accelerator systems. Often times, these are viewed by a human operator who then makes appropriate adjustments to the machine. Given recent advances in using convolutional neural networks (CNNs) for image processing, it should be possible to use image diagnostics directly in control routines (NN-based or otherwise). This is especially appealing for non-intercepting diagnostics that could run continuously during beam operation. Here, we show results of a first step toward implementing such a controller: our trained CNN can predict multiple simulated downstream beam parameters at the Fermilab Accelerator Science and Technology (FAST) facility's low energy beamline using simulated virtual cathode laser images, gun phases, and solenoid strengths.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Compact Low-Voltage, High-Power, Multi-beam Klystron for ILC: Initial Test Results

Initial test results of an L-band multi-beam klystron with parameters relevant for ILC are presented. The chief distinction of this tube from MBKs already developed for ILC is its low operating voltage of 60 kV, a virtue that implies considerable technological simplifications in the accelerator complex. To demonstrate the concept underlying the tubes design, a six-beamlet quadrant (a 54 inch high one-quarter portion of the full 1.3 GHz tube) was built and recently underwent initial tests, with main goals of demonstrating rated gun perveance, rated gain, and at least one-quarter of the full 10-MW rated power. Our initial three-day conditioning campaign without RF drive (140 microsec pulses @ 60 Hz) was stopped at 53% of full rated duty because of time-limits at the test-site; no signs appeared that would seem to prevent achieving full duty operation (i.e., 1.6 msec pulses @ 10 Hz). The subsequent tests with 10-15 microsec RF pulses confirmed the rated gain, produced output powers of up to 2.86 MW at 60 kV with high efficiency and 56 dB gain, and showed acceptable beam interception. These results suggest that a full version of the tube should be able to produce up to 11.5 MW. Follow-on tests are planned for later in 2015.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

A Dual-Lattice Discrete Element Model to Understand Hydraulic Fracturing in a Naturally Fractured System

Interaction between hydraulic fractures (HF) and natural fractures (NF) may lead to complex fracture networks as a consequence of branching and merging of the natural and hydraulically-induced/reopened fractures. Conventional simulation methods, with assumptions of homogeneous and continuous media, are not able to capture realistic fracture patterns in the presence of pre-existing natural fractures (open or healed). These natural discontinuities alter the local stress field and impact the fracturing fluid pressure distribution when hydraulically-driven fractures approach natural discontinuities. Modeling the propagation of one or more propagating hydraulic fractures in naturally fractured reservoirs should carefully consider the complex mechanical and hydraulic interactions between hydraulically-driven and natural fractures. A rigorous hydraulic fracturing model based on a coupled discrete element method (DEM) and conjugate network flow model is described in this work. The coupled DEM-network flow model conveniently accounts for both continuous poroelasticity and discrete natural fractures simultaneously and provides more realistic fracture growth patterns in low-permeability rocks. This dual lattice DEM-network flow model can capture both tension-induced rock failure and shear-induced natural discontinuity sliding and dilation. Simulation results revealed that reactivation of natural fractures becomes more difficult when the following conditions are present: larger magnitude of stress difference, higher intercepting angle between the natural fracture and the propagating hydraulic fracture (higher implies more orthogonal to the natural fracture), larger natural fracture cohesion and angle of internal friction and/or lower natural fracture permeability - leading to continued growth of the hydraulic fracture. The term stress difference was colloquially used in the preceding sentence. For clarity, we will define this as ΔS = S H,max – S h,min ). The quantitative results of numerous simulations reinforced the intuitive understanding of the underlying phenomena. Other simulations reinforced insights from laboratory experimentation and field measurements that lower injection rates and treating fluid viscosities facilitate preferential fluid intake into natural fractures. Finally, this simulation capability for predicting the nature of complex fracture networks potentially enables optimizing treatment design and completion strategy in naturally fractured reservoirs.

42 ENGINEERING↗
DOE OSTI2019

Proposed Enhanced Imaging Station in the 6-GeV Booster-to-Storage Ring Transport Line for APS Upgrade

The high charge per micropulse of up to 17 nC in the booster to storage ring transport line (BTS) for APS Upgrade will necessitate changes in the imaging station used to evaluate beam emittance in this key region. The original Chromox screen has recently been replaced by a YAG:Ce single crystal for immediate screen spatial resolution improvement down to <10 µm. However, the optical system also needs an upgrade with lenses and a digital camera to take full advantage of this enhancement. In addition, at the high areal charge densities expected, the YAG:Ce scintillator mechanism will saturate, or quench, leading to images larger than the actual beam size. To circumvent this effect, optical transition radiation (OTR) screens will be implemented. A proposed longer-range goal of a non-intercepting beam-size monitor using optical diffraction radiation techniques during top-up injection will also be addressed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Predictive guidance flight

The various technologies presented herein relate to utilizing predictive guidance during one or more phases of a trajectory flown by an interceptor during interception with a target. The trajectory of the interceptor comprises an initial phase, a predictive phase, and a final phase. The initial phase includes the launching of the interceptor and can be unguided. The predictive phase directs the interceptor towards the target, wherein the predictive phase utilizes predictive guidance to control the trajectory of the interceptor based upon a predicted location of the target relative to the current locations of the target and the interceptor. During the predictive phase, a motor(s) can be cycled on and off, causing a period(s) where the interceptor is being propelled by the ignited motor, and a period(s) where the interceptor is propelled by its own momentum after cessation of power from the motor, e.g., unpowered flight.

Spooner, Jeffrey T.↗
DOE OSTI2019

Proposed Enhanced Imaging Station in the 6-GeV Booster-to-Storage Ring Transport Line for APS Upgrade

The high charge per micropulse of up to 17 nC in the booster to storage ring transport line for APS Upgrade will necessitate changes in the imaging station used to evaluate beam emittance in this key region. The original Chromox screen has recently been replaced by a YAG:Ce single crystal for immediate screen spatial resolution improvement down to <10 µm. However, the optical system also needs an upgrade with lenses and a digital camera to take full advantage of this. In addition, at the high areal charge densities expected, the YAG:Ce scintillator mechanism will saturate, or quench, leading to images larger than the actual beam size. To circumvent this effect, optical transition radiation (OTR) screens will be implemented. A proposed longer-range goal of a non-intercepting beam-size monitor using optical diffraction radiation techniques during top-up injection will also be addressed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Concentric semi-circular split profiling for computed tomographic imaging of electronic beams

Apparatus and method for analyzing an electron beam including a circular sensor disk adapted to receive the electron beam, an inner semi-circular slit in the circular sensor disk; an outer semi-circular slit in the circular sensor disk wherein the outer semi-circular slit is spaced from the first semi-circular slit by a fixed distance; a system for sweeping the electron beam radially outward from the central axis to the inner semi-circular slit and outer second semi-circular slit; a sensor structure operatively connected to the circular sensor disk wherein the sensor structure receives the electron beam when it passes over the inner semi-circular slit and the outer semi-circular slit; and a device for measuring the electron beam that is intercepted by the inner semi-circular slit and the outer semi-circular slit.

42 ENGINEERING↗
DOE OSTI2020

Multicube retroreflector and retroreflector-based communication system

A “multicube” retroreflector may include “nested” corner cubes. Such a design combines the ease of fabrication of conventional corner cubes (e.g., stamping from a sheet) and the ability to easily and densely package them with a greater range of angles over which light will be reflected back towards the source. Such multicube retroreflectors may reflect 50% more light than corner cube retroreflectors. A retroreflector, or an array of retroreflectors, may be used as part of a communication system. A modulated retroreflector or an array thereof can form the basis of a unique communication system. For instance, by using a modulated retroreflector, or an array of such retroreflectors, a host system (e.g., an aircraft) can receive data from a remote system (e.g., a drone, an air-dropped sensor package, etc.) in a way that is difficult to intercept, and minimizes the power, computation, and antenna pointing requirements for the remote system.

42 ENGINEERING↗
DOE OSTI2018

Discovery and analysis of a blind geothermal system in southeastern Gabbs Valley, Western Nevada

This study assessed the potential for high-temperature (≥130°C) blind geothermal systems in southeastern Gabbs Valley by employing a geothermal play fairway analysis approach involving integration of geologic, geophysical, and geochemical datasets. Gabbs Valley is a complex, tectonically active basin within the Great Basin on the boundary between the transtensional central Walker Lane domain and extensional Basin and Range province. The termination of the Petrified Springs fault, a major dextral fault of the central Walker Lane, in an array of normal faults indicates that southeastern Gabbs Valley occupies a displacement transfer zone, which is a favorable structural setting for geothermal activity. The displacement transfer zone is a structurally complicated area with many faults of varying geometries, kinematics, and ages. A substantial northwest-trending gravity high within the south-central part of southeastern Gabbs Valley is produced from offsets along concealed northwest-striking dextral-normal faults that intersect strands of north-northeast-to east-northeast-striking normal faults. This area of tightly spaced faults and fault intersections is a particularly favorable structural setting within the broader-scale displacement transfer zone. Multiple lines of direct and indirect evidence suggest the presence of a relatively high-temperature (≥130°C) blind geothermal system in this area, including collocated intersecting gravity gradients, magnetic-low, low-resistivity, and 2-m temperature anomaly. Potentially related, water samples from agricultural wells ~7 km northwest of the 2-m anomaly yield geothermometers indicating subsurface fluid temperatures of 130-140°C. Six temperature-gradient holes were drilled to target the extent of the shallow-temperature and geophysical anomalies to define the geothermal system in southeastern Gabbs Valley. Two wells contained high temperatures exceeding boiling with bottom-hole temperatures ii of 114.5°C and 124.9°C, respectively, and the remaining wells displayed elevated to background temperatures ranging from 79.2°C to 28.7°C. The observed temperature gradients for the two hottest drill holes necessitate drill-hole intercepts of convecting hydrothermal fluids. The 2-m survey is spatially and thermally consistent with the temperature-gradient holes and constrains the core of upflow at a shallow depth interval (<250m) to an area <0.5-1 km west-southwest of the hottest drill hole. The zone of inferred upwelling occupies the area corresponding to the center of the magnetic-low. This project has several significant implications. The newly discovered blind geothermal system in southeastern Gabbs Valley may be capable of supporting a binary-type geothermal power plant. This detailed study provides an initial validation of the play fairway approach to geothermal exploration. It also demonstrates both the broad applicability of the play fairway exploration strategy and the large untapped potential for commercial-grade blind geothermal systems in many of the basins in the Great Basin region.

15 GEOTHERMAL ENERGY↗
DOE OSTI2019

Expert Q&A: Why a Hypersonic Vehicle Flight Test Ban Is Not a Good Idea

Hypersonic Vehicle (HV) development has been pursued since the late 1950s. These vehicles could significantly cut the cost of accessing space, lessen flight time anywhere on the planet to two to three hours, and be used as weapons that would be extremely difficult to intercept. Although considerable progress has been made, hypersonic flight remains in the development and testing phase.

HGV↗
DOE OSTI2021

Systems and methods for electronic communication with a device using an unknown communications protocol

Various technologies for communicating with systems that communicate using an unknown communications protocol are described herein. A transceiver intercepts a plurality of communications exchanged between two or more transceivers on a communications network. Pattern-recognition algorithms are executed over the plurality of communications, and features of an unknown communications protocol that governs the communications between the two or more transceivers are inferred based upon output of the pattern-recognition algorithms. A communication is formatted based upon the inferred features of the unknown communications protocol, and the communication transmitted to one or more systems on the communications network by way of the transceiver. The communication at least partially conforms to the unknown communications protocol, and so may be interpreted by systems on the network.

Patel, Silpan M.↗