Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “rf source”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,117 records · Page 62
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Characteristics of RF resulting from dielectric discharges

This paper presents measurements of the electromagnetic radiation pulses and the replacement current pulses which result from the breakdown of Mylar and Kapton samples. The observed dependence of the characteristics of the replacement current pulse as a function of electron beam energy is discussed. The characteristics of the electromagnetic radiation pulses are also analyzed in the text of this paper. The source of the irradiating electrons is a monoenergetic electron beam whose energy was varied from 12.5 KeV to 25 KeV.

Leung, P.↗
DOE OSTI2012

The High Intensity Horizon at Fermilab

Fermilab's high intensity horizon is 'Project-X' which is a US led initiative with strong international participation that aims to realize a next generation proton source that will dramatically extend the reach of Intensity Frontier research. The Project-X research program includes world leading sensitivity in long-baseline and short-baseline neutrino experiments, a rich program of ultra-rare muon and kaon decays, opportunities for next-generation electric dipole moment experiments and other nuclear/particle physics probes, and a platform to investigate technologies for next generation energy applications. A wide range of R&D activities has supported mission critical accelerator subsystems, such as high-gradient superconducting RF accelerating structures, efficient RF power systems, cryo-modules and cryogenic refrigeration plants, advanced beam diagnostics and instrumentation, high-power targetry, as well as the related infrastructure and civil construction preparing for a construction start of a staged program as early as 2017.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2019

Bremsstrahlung dose rates during the conditioning of the superconducting RF cavities of the NSLS-II storage ring

NSLS-II storage ring currently operates with two single-cell Cornell Electron Storage Ring (CESR) type niobium cavities at 500 MHz with a Q value of 79,000 [1,2] both in one straight section in cell 24. During the maintenance period, the cavities have to be conditioned to be ready for operation. The cavities are source of bremsstrahlung radiation due to the field emission and multipacting processes.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Development of ROACH firmware for microwave multiplexed X-ray TES microcalorimeters

We are developing room temperature electronics based upon the ROACH platform for reading out microwave multiplexed X-ray TES. ROACH is an open-source hardware and software platform featuring a large Xilinx Field Programmable Gate Array (FPGA), Power PC processor, several 10GB Ethernet SFP+ interfaces, and a collection of daughter boards for analog signal generation and acquisition. The combination of a ROACH board, ADC/DAC conversion daughter boards, and hardware for RF mixing allows for the generation and capture of multiple RF tones for reading out microwave multiplexed x-ray TES microcalorimeters. The FPGA is used to generate multiple tones in base band, from 10MHz to 250MHz, which are subsequently mixed to RF in the multiple GHz range and sent through the microwave multiplexer. The tones are generated in the FPGA by storing a large lookup table in Quad Data Rate (QDR) SRAM modules and playing out the waveform to a DAC board. Once the signal has been modulated to RF, passed through the microwave multiplexer, and has been modulated back to base band, the signal is digitized by an ADC board. The tones are modulated to 0Hz by using a FPGA circuit consisting of a polyphase filter bank, several Xilinx FFT blocks, Xilinx CORDIC blocks (for converting to magnitude and phase), and special phase accumulator circuit for mixing to exactly 0Hz. Upwards of 256 channels can be simultaneously captured and written into a bank of 256 First-In-First-Out (FIFO) memories, with each FIFO corresponding to a channel. Individual channel data can be further processed in the FPGA before being streamed through a 10GB Ethernet fiber-optic interface to a Linux system. The Linux system runs software written in Python and QT C++ for controlling the ROACH system, capturing data, and processing data.

Firmware↗
NASA NTRS1988

A 30 GHz monolithic receive module technology assessment

This report is a technology assessment relevant to the 30 GHz Monolithic Receive Module development. It is based on results obtained on the present NASA Contract (NAS3-23356) as well as on information gathered from literature and other industry sources. To date the on-going Honeywell program has concentrated on demonstrating the so-called interconnected receive module which consists of four monolithic chips - the low noise front-end amplifier (LNA), the five bit phase shifter (PS), the gain control amplifier (GC), and the RF to IF downconverter (RF/IF). Results on all four individual chips have been obtained and interconnection of the first three functions has been accomplished. Future work on this contract is aimed at a higher level of integration, i.e., integration of the first three functions (LNA + PS + GC) on a single GaAs chip. The report presents the status of this technology and projections of its future directions.

Geddes, J.↗
DOE OSTI2012

Higher Order Modes Damping Analysis for the SPX Deflecting Cavity Cryomodule

A single-cell superconducting deflecting cavity operating at 2.812 GHz has been proposed and designed for the Short Pulse X-ray (SPX) project for the Advanced Photon Source upgrade. A cryomodule of 4 such cavities will be needed to produce the required 2-MV deflecting voltage. Each deflecting cavity is equipped with one fundamental power coupler (FPC), one lower order mode (LOM) coupler, and two higher order mode (HOM) couplers to achieve the stringent damping requirements for the unwanted modes. The damping of the HOM/LOM modes below the beampipe cutoff has been analyzed in the single cavity geometry and shown to meet the design requirements. The HOMs above beam pipe cutoff in the 4-cavity cyromodule, however, may result in cross coupling which may affect the HOM damping and potentially trapped modes between the cavities which could produce RF heating to the beamline bellows and even be detrimental to the beam. We have evaluated the HOM damping and trapped modes in the 4-cavity cryomodule using the parallel finite element EM code ACE3P developed at SLAC. We will present the results of the cryomodule analysis in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Conceptual Design and Performance Considerations for Superconducting Magnets in the Material Plasma Exposure eXperiment

An important step toward the advent of nuclear fusion as a future power source is the development of plasmafacing materials that can function as designed for a long period of time. While ITER and other devices including Wendelstein 7-X and the Joint European Torus will provide insight into divertor and first wall performance, a dedicated device to advance the understanding of material performance in the representative plasma environments is needed. The Material Plasma Exposure eXperiment has been proposed as a linear plasma device to generate and to direct fusion reactor-like plasma energy and particle flux at the target materials with electron temperatures of 1-15 eV and electron densities of 10 20 -10 21 m -3 . Given that the requirements for radio frequency (RF) heating on-axis field are no greater than 2.5 T and the warm bore diameters must be between 60 cm and 1.5 m, the conceptual design was developed for the experiments on a set of superconducting magnets carried out using commercially available NbTi superconductors. This conceptual design evaluated the cryogenic heat loads, mechanical loads, and quench protection to ensure that the current design is compatible with current technologies. In addition, an alternative evaluation of this design relative to ReBCO high-temperature superconducting magnets determined the conditions under which these technologies could be advantageous.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

Ion beams extraction and measurements of plasma parameters on a multi-frequencies microwaves large bore ECRIS with permanent magnets

We have developed an all-permanent magnet large bore electron cyclotron resonance ion source (ECRIS) for broad ion beam processing. The cylindrically comb-shaped magnetic field configuration is adopted for efficient plasma production and good magnetic confinement. To compensate for disadvantages of fixed magnetic configuration, a traveling wave tube amplifier (TWTA) is used. In the comb-shaped ECRIS, it is difficult to achieve controlling ion beam profiles in the whole inside the chamber by using even single frequency-controllable TWTA (11-13GHz), because of large bore size with all-magnets. We have tried controlling profiles of plasma parameters and then those of extracted ion beams by launching two largely different frequencies simultaneously, i.e., multi-frequencies microwaves. Here we report ion beam profiles and corresponding plasma parameters under various experimental conditions, dependence of ion beams against extraction voltages, and influence of different electrode positions on the electron density profile.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Development of a cryocooler conduction-cooled 650 MHz SRF cavity operating at ~10 MV/m cw accelerating gradient

SRF cavities for particle acceleration are conventionally operated immersed in a bath of liquid helium at 4.2 K and below. Although this cooling configuration is practically and economically viable for large scientific accelerator installations, it may not be so for smaller accelerators intended for industrial applications such as the treatment of wastewater, sludge, flue gases, etc. In this paper, we describe a procedure to operate SRF cavities without liquid helium that can be used to construct electron-beam sources for industrial applications of electron irradiation (1-10 MeV electron energy). In this procedure, an elliptical single-cell 650 MHz niobium-tin coated niobium cavity is coupled to a closed-cycle 4.2 K cryocooler using high purity aluminum thermal links. The cryocooler conductively extracts heat (RF dissipation) from the cavity without requiring liquid helium around the cavity. We present construction details of this cryocooler conduction-cooling technique and systematic experiments that have demonstrated ~10 MV/m cw gradient on the cavity. By straightforward scaling up the cavity length and number of cryocoolers, the technique will provide the complete range of 1-10 MeV electron energy for industrial applications.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Human Perceptions of Colour Rendition at Different Chromaticities

An experiment was conducted to evaluate how subjective impressions of a light source’s color quality depend upon color rendition and chromaticity. Thirty-three participants each evaluated 50 lighting scenes in a 3.7 m by 5.5 m room filled with objects selected to cover a range of hue, saturation, and lightness. The lighting scenes included five chromaticity groups, specified here using correlated color temperature (CCT) and Duv¬: 2700 K, 0.000; 2700 K, -0.007; 3500 K, 0.000; 4300 K, 0.000; 4300 K, -0.007. Within each group were the same 10 systematically-varied color rendition conditions. The Illuminating Engineering Society (IES) TM-30-15 Fidelity Index (Rf) values ranged from 60 to 93, IES TM-30 Gamut Index (Rg) values from 88 to 124, and IES TM-30 Hue Angle Bin 1 Chroma Shift (Rcs,h1) values from -15% to 28%. All lighting scenes had the same nominal illuminance. Participants were asked to rate each scene on eight point scales for saturated-dull, normal-shifted, and like-dislike, as well as choosing whether they found the scenes to be acceptable or unacceptable. The findings suggest that color rendition preferences can vary with chromaticity, but do not support absolute preferences for negative Duv values. At 4300 K, there was no difference in rated preference, saturation, normalness, or acceptability between the two groups with different Duv values. However, at 2700 K, there was a significant difference for all four perceptions, with the negative Duv sources being rated more liked (on average)—and for nine of the ten individual color rendition conditions. Further, across all levels of red chroma shift—according to TM-30 values Rcs,h1, Rcs,h15, and Rcs,h16—the room was rated as more saturated at 2700 K than at 3500 K or 4300 K (regardless of Duv); in turn, increases in red saturation were less preferred and less acceptable at 2700 K than the other CCTs. The differences in ratings between the chromaticity groups were substantially smaller than the range in ratings for the 10 color rendition conditions in each group, and on average the best fit model uses a combination of Rf, Rcs,h16, and potentially Rg. Despite the differences in ratings for chromaticity groups, a set of criteria identified in previous research for preferred color rendition in this generic application could be used for all groups. Those criteria are Rf = 74, -1% = Rcs,h1 = 15%, and Rg = 100.

Royer, Michael P.↗
DOE OSTI2019

Enhanced polarization of low pressure 3 He through metastability exchange optical pumping at high field

Here, we report high steady-state nuclear polarization of 1 torr 3 He gas nuclei via metastability exchange optical pumping at magnetic fields above 2 T. The introduction of highly polarized 3 He gas into Brookhaven’s Electron Beam Ion Source would enable a new, polarized 3 He ion source for use at the Relativistic Heavy Ion Collider and a future Electron–Ion Collider facility. By adapting recent developments in high field metastability exchange optical pumping for higher pressure gas, we have successfully polarized 1 torr 3 He sealed cells in the EBIS solenoid. Through careful manipulation of the RF discharge parameters, polarizations above 80% were attained at 2, 3 and 4 T, with 89% being reached at 3 T with a 664 s relaxation time.

43 PARTICLE ACCELERATORS↗
NASA NTRS2021

Acoustic Communication in Deep Ice at Ocean Worlds

One of NASA priorities is the in-situ exploration of ocean worlds in the solar system where potentially there might be life under the ice shell. This requires reaching the ocean below extremely cold through significant deep ice. Jupiter’s moon, Europa, is such a challenging body, where it is estimated to have a 40 km thick ice shell. An approach for reaching the ocean has been conceived using a melting probe Cryobot concept that has been studied for a potential future mission. A lander is assumed to be the platform from which the Cryobot would be deployed. The ice penetrating vehicle concept consists of a cylindrical, narrow-body probe that encases a radioisotope heat/power source that would be used to do the penetration by melting through the icy crust. The baseline design of the probe includes a suite of science instruments to analyze the ice during descent and the liquid ocean underneath. For communication, a set of fiber optic wire as well as wireless RF in the very cold porous top layer is assumed, and then acoustic modules would be used for the communication in warmer denser ice over distance of 25 km between the modules. In addition to the acoustic communication modules, a sonar is part of the concept, for obstacle avoidance. The focus of this paper is on the use of elastic waves in the 1kHz range.

Lih, Shyh-Shiuh↗
DOE OSTI2022

Design Enhancements for the SNS RFQ Coaxial Coupler

The H⁻ ion linear accelerator at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory operates with reliability that routinely surpasses 90% during scheduled beam operation. With the ambitious goal of eventually achieving at least 95% availability, several upgrade and improvement projects are ongoing. One such project is the modification of the coaxial couplers that transfer radio frequency (RF) power to the accelerator’s Radio Frequency Quadrupole (RFQ). The proposed modification utilizes stub sections and capacitive coupling to construct a physically separable assembly with DC isolation. With a separated coupler assembly, the section that includes the magnetic coupling loop can be permanently mounted to the RFQ which would eliminate the need to re-adjust the couplers after maintenance activities, upgrades, and repairs. Additionally, the modified design would provide increased multipaction suppression with DC biasing and potentially lower thermal gradients across the device. This paper presents the design and simulation results of the project.

Toby, George↗
DOE OSTI2013

High Pressure Gas Filled RF Cavity Beam Test at the Fermilab MuCool Test Area

The high energy physics community is continually looking to push the limits with respect to the energy and luminosity of particle accelerators. In the realm of leptons, only electron colliders have been built to date. Compared to hadrons, electrons lose a large amount of energy when accelerated in a ring through synchrotron radiation. A solution to this problem is to build long, straight accelerators for electrons, which has been done with great success. With a new generation of lepton colliders being conceived, building longer, more powerful accelerators is not the most enticing option. Muons have been proposed as an alternative particle to electrons. Muons lose less energy to synchrotron radiation and a Muon Collider can provide luminosity within a much smaller energy range than a comparable electron collider. This allows a circular collider to be built with higher attainable energy than any present electron collider. As part of the accelerator, but separate from the collider, it would also be possible to allow the muons to decay to study neutrinos. The possibility of a high energy, high luminosity muon collider and an abundant, precise source of neutrinos is an attractive one. The technological challenges of building a muon accelerator are many and diverse. Because the muon is an unstable particle, a muon beam must be cooled and accelerated to the desired energy within a short amount of time. This requirement places strict requisites on the type of acceleration and focusing that can be used. Muons are generated as tertiary beams with a huge phase space, so strong magnetic fields are required to capture and focus them. Radio frequency (RF) cavities are needed to capture, bunch and accelerate the muons. Unfortunately, traditional vacuum RF cavities have been shown to break down in the magnetic fields necessary for capture and focusing.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Higher Order Modes Damping Analysis for the SPX Deflecting Cavity Cyromodule

A single-cell superconducting deflecting cavity operating at 2.815 GHz has been proposed and designed for the Short Pulse X-ray (SPX) project for the Advanced Photon Source (APS) upgrade. A cryomodule of 4 such cavities will be needed to produce the required 2-MV deflecting voltage. Each deflecting cavity is equipped with one fundamental power coupler (FPC), one lower order mode (LOM) coupler, and two higher order mode (HOM) couplers to achieve the stringent damping requirements for the unwanted modes. The damping of the LOM/HOM below the beampipe cutoff has been analyzed in the single cavity geometry and shown to meet the design requirements. The HOM above the beampipe cutoff in the 4-cavity cyromodule, however, may result in cross coupling which may affect the HOM damping and potentially be trapped between the cavities which could produce RF heating to the beamline bellows. We have evaluated the HOM damping in the 4-cavity cryomodule using the parallel finite element EM code suite ACE3P developed at SLAC. We will present the results of the cryomodule analysis in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

An overview of Booster and AGS Polarized Proton Operations during Run 17

There were only a few differences in the setup between this year’s Polarized Proton run and the previous one (Run 15). Consequently, this note will focus on these differences as well as a few more notable studies done during the course of the run. This year, the Booster input intensity was kept around 7e11 for the majority of the run whereas in Run 15 it was kept around 9e11. It was lowered because there was some indication that the source polarization was higher with this lower input. Some of the polarization measurements that motivated this change will be discussed. Both the emittance and polarization on the AGS flattop show intensity dependence, thought to be related to the peak current, especially early in the AGS acceleration ramp. In Run 15, the AGS Rf was configured for h=8, but in this run h=6 was used to reduce the peak current and also to allow for the possibility of using a dual harmonic to reduce it further. Eventually, a dual harmonic configuration was used for the first 100 ms or so of the AGS acceleration cycle. Two cavities were set to h=12 and phased differently than the other 8 to accomplish this. Quad pumping was also used at Booster extraction to make the bunch injected into the AGS wider in order to match the dual harmonic bucket right at injection. This configuration, which was used for the majority of the run, will be described. Measurements of the intensity dependence of the transverse emittance and polarization with and without it will be compared.

43 PARTICLE ACCELERATORS↗
NASA NTRS1980

Adherence of ion beam sputter deposited metal films on H-13 steel

An electron bombardment argon ion source was used to sputter deposit 17 different metal and metal oxide films ranging in thickness from 1 to 8 micrometers on H-13 steel substrates. The film adherence to the substrate surface was measured using a tensile test apparatus. Comparisons in bond strength were made between ion beam, ion plating, and RF deposited films. A protective coating to prevent heat checking in H-13 steel dies used for aluminum die casting was studied. The results of exposing the coated substrates to temperatures up to 700 degrees are presented.

Mirtich, M. J.↗