1290-MHz Radar Wind Profiler: Precipitation Moments, operating in low power mode
1290-MHz Radar Wind Profiler: Precipitation Moments, operating in low power mode
1290 MHz↗
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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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1290-MHz Radar Wind Profiler: Wind Moments, operating in low power mode
1290-MHz Radar Wind Profiler: Wind Moments, operating in low power mode
1290 MHz↗
1290-MHz Radar Wind Profiler: Precipitation Spectra, operating in low power mode
1290-MHz Radar Wind Profiler: Precipitation Spectra, operating in low power mode
1290 MHz↗
1290-MHz Radar Wind Profiler: Wind Spectra, operating in low power mode
1290-MHz Radar Wind Profiler: Wind Spectra, operating in low power mode
1290 MHz↗
1290-MHz Radar Wind Profiler: Precipitation Averages, operating in low power mode
1290-MHz Radar Wind Profiler: Precipitation Averages, operating in low power mode
1290 MHz↗
Multistage depressed collector for dual mode operation
A depressed collector which captures the spent electrons of a microwave transmitting tube at high efficiency in both high and low power modes of operation is described. The collector comprises entrance and end electrodes, the end electrode having a spike extending toward entrance electrode. Intermediate electrodes and the entrance electrode each have a central aperture and, together, these electrodes capture most high power mode spent electrons. The apertures of the electrodes increase in size in a downstream direction. To capture low power mode spent electrons a low power mode electrode is positioned between the last intermediate electrode and the end electrode. This electrode has a central aperture preferably smaller but no larger than that of the last intermediate electrode. An auxiliary low power mode electrode may be added having a central aperture larger than that of the low power mode electrode. All of the electrodes are at voltages provided by a voltage divider connected between a potential.
Kosmahl, H. C.↗
The use of low power dual mode nuclear thermal rocket engines to support space exploration missions
The evolution of dual mode concepts is presented, focusing on advantages and problems associated with both low and high temperature dual mode conversion systems. It is concluded that dual mode nuclear thermal rocket (NTR) systems using high temperature Brayton cycle conversion technology offer a high payoff enhancement of conventional NTR, with a comparatively minor increase of technological challenge. It is recommended that NTR engines be designed so that dual mode conversion systems can be attached to them in a modular way, thus enabling the production of electric power on all missions where it is needed.
Zubrin, Robert M.↗
A 20 GHz, high efficiency dual mode TWT for the ACTS program
The development of a 50 W/10 W dual mode K-band downlink TWT is examined, and its performance is evaluated. The designs of the electron gun, RF circuit, and collector for the TWT, which is enclosed in a capsule, are described. It is observed that the high power mode (HPM) power output is at 50 GHz and the low power mode (LPM) output is at 12 GHz; the saturated gain is 52.5 dB for HPM and 3 dB for LPM; the AM-PM is 4.2 dB; the HPM dc power output is 104 W; and the LPM dc output is 42 W; and the efficiency is 45 percent for the HPM and 28.6 percent for the LPM.
Muennemann, Frank↗
Development of simplified external control techniques for broad area semiconductor lasers
The goal of this project was to injection lock a 500 mW broad area laser diode (BAL) with a single mode low power laser diode with injection beam delivery through a single mode optical fiber (SMF). This task was completed successfully with the following significant accomplishments: (1) injection locking of a BAL through a single-mode fiber using a master oscillator and integrated miniature optics; (2) generation of a single-lobed, high-power far-field pattern from the injection-locked BAL that steers with drive current; and (3) a comprehensive theoretical analysis of a model that describes the observed behavior of the injection locked oscillator.
Davis, Christopher C.↗
MRI Load Profile Characterization Across Scanner Manufacturers and Field Strengths - Opportunities for Energy Efficiency Improvements
Radiology plays a vital role in patient care, but a reliance on energy-intensive imaging equipment leads to significant greenhouse gas emissions. MRI scanners can consume up to 80% of their total energy during times when there is not active patient imaging. Characterizing MRI average power and time to enter low-power mode across scanning protocols can identify energy efficiency opportunities.
emissions↗
A 20 Gbps PAM4 data transmitter ASIC for particle physics experiments
We present the design and test results of a novel data transmitter ASIC operating up to 20.48 Gbps with 4-level Pulse-Amplitude-Modulation (PAM4) for particle physics experiments. This ASIC, named GBS20, is fabricated in a 65 nm CMOS technology. Two serializers share a 5.12 GHz Phase Locked Loop (PLL) clock. The outputs from the serializers are combined into a PAM4 signal that directly drives a Vertical-Cavity-Surface-Emitting-Laser (VCSEL). The input data channels, each at 1.28 Gbps, are scrambled with an internal 2$^{7}$-1 Pseudo-Random Binary Sequence (PRBS), which also serves as a frame aligner. GBS20 is tested to work at 10.24 and 20.48 Gbps with a VCSEL-based Transmitter-Optical-Subassembly (TOSA). The power consumption of GBS20 is below 238 mW and reduced to 164 mW in the low-power mode.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Systems analysis of a low-acceleration research facility
The Low-Acceleration Research Facility (LARF), an unmanned free-flier that is boosted from low-earth orbit to a desired altitude using an orbital transfer vehicle is discussed. Design techniques used to minimize acceleration-causing disturbances and to create an ultra-quiet workshop are discussed, focusing on residual acceleration induced by the environment, the spacecraft and experiments. The selection and integration of critical subsystems, such as electrical power and thermal control, that enable the LARf to accomodate sub-microgravity levels for extended periods of time are presented, including a discussion of the Low-Acceleration Module, which will supply the payload with 25.0 kW of power, and up to 11.8 kW in the low-power mode. Also, the data management, communications, guidance, navigation and control, and structural features of supporting subsystems are examined.
Martin, Gary L.↗
GBT20, a 20.48 Gbps PAM4 Optical Transmitter Module for Particle Physics Experiments
We present a pluggable radiation-tolerant 4-level Pulse-Amplitude-Modulation (PAM4) optical transmitter module called GBT20 (Giga-Bit Transmitter at 20 Gbps) for particle-physics experiments. GBT20 has an OSFP or firefly connector to input 16-bit data each at 1.28 Gbps. The GBT20 drives a VCSEL die with an LC lens or a VCSEL TOSA and interfaces an optical fiber with a standard LC connector. The minimum module, including the host connector, occupies 41 mm x 13 mm x 6 mm. At 20.48 Gbps, the minimum Transmitter Dispersion Eye Closure Quaternary (TDECQ) is around 0.7 dB. The power consumption is around 164 mW in the low-power mode. The SEE cross-section is below 7.5x10^(-14) cm^2. No significant performance degrades after a TID of 5.4 kGy.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Recurrence in truncated Boussinesq models for nonlinear waves in shallow water
The rapid spatial recurrence of weakly nonlinear and weakly dispersive progressive shallow-water waves is examined using a numerical integration technique on the discretized and truncated form of the Boussinesq equations. This study primarily examines recurrence in wave fields with Ursell number O(1) and characterizes the sensitivity of recurrence to initial spectral shape and number of allowed frequency modes. It is shown that the rapid spatial recurrence is not an inherent property of the considered Boussinesq systems for evolution distances of 10-50 wavelengths. The main result of the study is that highly truncated Boussinesq models of resonant shallow-water ocean surface gravity waves predict rapid multiple recurrence cycles, but that this is an artifact dependent on the number of allowed modes. For initial conditions consisting of essentially all energy concentrated in a single mode, damping of the recurrence cycles increases as the number of low-power background modes increases. When more than 32 modes are allowed, the recurrence behavior is relatively insensitive to the number of allowed modes.
Elgar, Steve↗
Fabrication and testing of the transition section between modules of a wakefield accelerator
The fabrication process is presented for a typical transition section located between each cylindrical corrugated waveguide structure comprising the wakefield accelerator module. The transition section includes couplers for extracting the 180 GHz TM 01 accelerating mode and separate couplers for extracting the 190 GHz HE 11 dipole mode, both modes induced by the electron bunch traversing the cylindrical corrugated waveguide structure. Extraction of the high-power accelerating mode reduces the heat load due to the subterahertz wave power dissipation within the corrugated accelerating structure. Extraction of the low-power dipole mode serves the purpose of detecting the electron bunch transverse oscillations within the wakefield accelerator and identifying the onset of beam breakup instability. Comprehensive testing of the fully functional transition section with an electron beam was done at the Accelerator Test Facility in Brookhaven National Laboratory which verified the functionality of the transition section. Published by the American Physical Society 2024
43 PARTICLE ACCELERATORS↗
Pulsed Operation of an Ion Accelerator
Electronic circuitry has been devised to enable operation of an ion accelerator in either a continuous mode or a highpeak power, low-average-power pulsed mode. In the original intended application, the ion accelerator would be used as a spacecraft thruster and the pulse mode would serve to generate small increments of impulse for precise control of trajectories and attitude. The present electronic drive circuitry generates the extraction voltage in pulses. Pulse-width modulation can affect rapid, fine control of time-averaged impulse or ion flux down to a minimum level much lower than that achievable in continuous operation.
Wirz, Richard↗
Frequency‐Locked Wireless Multifunctional Surface Acoustic Wave Sensors
Abstract Surface acoustic waves (SAWs) have shown great potential for developing sensors for structural health monitoring (SHM) and lab‐on‐a‐chip (LOC) applications. Existing SAW sensors mainly rely on measuring the frequency shifts of high‐frequency (e.g., >0.1 GHz) resonance peaks. This study presents frequency‐locked wireless multifunctional SAW sensors that enable multiple wireless sensing functions, including strain sensing, temperature measurement, water presence detection, and vibration sensing. These sensors leverage SAW resonators on piezoelectric chips, inductive coupling‐based wireless power transmission, and, particularly, a frequency‐locked wireless sensing mechanism that works at low frequencies (e.g., <0.1 GHz). This mechanism locks the input frequency on the slope of a sensor's reflection spectrum and monitors the reflection signal's amplitude change induced by the changes of sensing parameters. The proof‐of‐concept experiments show that these wireless sensors can operate in a low‐power active mode for on‐demand wireless strain measurement, temperature sensing, and water presence detection. Moreover, these sensors can operate in a power‐free passive mode for vibration sensing, with results that agree well with laser vibrometer measurements. It is anticipated that the designs and mechanisms of the frequency‐locked wireless SAW sensors will inspire researchers to develop future wireless multifunctional sensors for SHM and LOC applications.
Bo, Luyu↗
Intelligent subsystem interface for modular hardware system
A single chip application specific integrated circuit (ASIC) which provides a flexible, modular interface between a subsystem and a standard system bus. The ASIC includes a microcontroller/microprocessor, a serial interface for connection to the bus, and a variety of communications interface devices available for coupling to the subsystem. A three-bus architecture, utilizing arbitration, provides connectivity within the ASIC and between the ASIC and the subsystem. The communication interface devices include UART (serial), parallel, analog, and external device interface utilizing bus connections paired with device select signals. A low power (sleep) mode is provided as is a processor disable option.
Krening, Douglas N.↗