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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Summary of RF Technology Program Activities, October 2013 - September 2017

The goals of the National RF Research and Development Program (NRRDP) are to advance the basic understanding of high-power radio frequency (RF) in a plasma environment, and to maintain the high-power transmitters and cooling water systems required to support the ITER Ion Cylcotron Range of Frequencies (ICRF) transmission line high power component testing and operation of the Proto-Material Plasma Exposure eXperiment (MPEX) device. The work includes the study of the RF sheath, and development of RF-related diagnostics. These include active and passive spectroscopic diagnostics that can provide local and line integrated measurements of RF and Direct Current (DC) electric fields in the edge plasma of fusion devices, as well as measurements of other parameters. One of these, the Doppler Free Saturation Spectroscopy (DFSS) diagnostic, utilizes a laser beam split into two intersecting, counter-propagating pump and probe beams, whose intersection defines the measurement region. DFSS has demonstrated measurements of atomic spectra with 500 times greater resolution than passive Optical Emission Spectroscopy (OES). This allows Stark effect based electric field measurements to be made with two orders of magnitude high sensitivity than with OES. Measurements have been made using an ORNL electron-cyclotron resonant (ECR) plasma source producing densities up to 10 19 m -3 , in the vicinity of an RF-biased planar electrode.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Design of High Efficiency High Power Electron Accelerator Systems Based on Normal Conducting RF Technology for Energy and Environmental Applications

The goal of this project was to perform engineering design studies of three extremely high efficiency electron accelerators with the following parameters [1]: 2 MeV output beam energy and 1 MW average beam power; 10 MeV output energy and 10 MW; 10 MeV output energy and 1 MW. These linacs are intended for energy and environmental applications [2]. We based our designs on normal conducting radio-frequency technology. We have successfully reached this goal where we show rf-to-beam efficiency of 96.7 %, 97.2 %, and 79.6 % for these linacs.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

RF Technologies for Future Colliders

Particle colliders remain indispensable scientific instruments to discover and study new elementary particles and fundamental forces of nature. Whether the collider is a factory (used to improve precision of measuring properties of already discovered particles or to enable studies of rare decay channels), an energy frontier machine (aimed at discovering new particles and forces), a heavy ion collider (allowing studies of what the universe looked like in the early moments after its creation), or an electron-hadron collider (where electrons are used for probing heavy ions or protons to study the fundamental force binding all visible matter), the radio frequency technologies play a key role in enabling the machine to reach its goals. This article considers challenges presented to the radio frequency technologies by the next generation of particle colliders and reviews R&D approaches and directions to address these challenges.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

RF Accelerator Technology R&D: Report of AF7-rf Topical Group to Snowmass 2021

Accelerator radio frequency (RF) technology has been and remains critical for modern high energy physics (HEP) experiments based on particle accelerators. Tremendous progress in advancing this technology has been achieved over the past decade in several areas highlighted in this report. These achievements and new results expected from continued R&D efforts could pave the way for upgrades of existing facilities, improvements to accelerators already under construction (e.g., PIP-II), well-developed proposals (e.g., ILC, CLIC), and/or enable concepts under development, such as FCC-ee, CEPC, C 3 , HELEN, multi-MW Fermilab Proton Intensity Upgrade, future Muon Colloder, etc. Advances in RF technology have impact beyond HEP on accelerators built for nuclear physics, basic energy sciences, and other areas. Recent examples of such accelerators are European XFEL, LCLS-II and LCLS-II-HE, SHINE, SNS, ESS, FRIB, and EIC. To support and enable new accelerator-based applications and even make some of them feasible, we must continue addressing their challenges via a comprehensive RF R&D program that would advance the existing RF technologies and explore the nascent ones.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

High-brightness electron injectors for high-duty cycle X-ray free electron lasers

The successful development in the last two decades of X-ray free electron lasers (FELs) with their revolutionary brightness performance has been tightly dependent on the parallel development of electron guns and injectors capable of providing the high-brightness electron beams required by FELs lasing at these short wavelengths. The ultimate brightness delivered by a linear accelerator (linac) is already set at its injector and the remaining part of the accelerator can be only designed to preserve the injector performance. The technology to be used for the accelerator part of an X-Ray FEL strongly depends on the duty-cycle at which the FEL operates. Normal-conducting, room-temperature, copper-based radio frequency (RF) technology is typically used for low duty-cycles of up to approximately 10 −3 . For higher duty-cycles and up to continuous wave (CW) operation, the linac must rely on superconductive RF technology because, with the higher duty-cycle, the increasingly higher power dissipated in normal conducting RF structures becomes excessive for the warm technology. The situation changes in the lower energy part of the accelerator, where injector schemes, based on direct current, normal-conducting, and superconducting RF electron guns, are demonstrating the beam quality performance required by high-duty-cycle X-ray FELs. In this paper we start with a description of the requirements for such injectors, followed by an overview of the pursued technologies and schemes, and by a discussion on the main differences in terms of beam dynamics between low and high duty-cycle injectors.

Sannibale, Fernando↗
DOE OSTI2018

Solid-State Ultra-High Power Amplifier Modules Based on 100 V RF GaN Technology for LINACS Operating at 325 and 650 MHz

Purpose / objectives. This research project explores the groundwork for developing a new high efficiency, high reliability and cost effective radio frequency technology to be used in power sources for future linear accelerators. The frequencies of operation are 650 and 325 MHz, in use at Fermi National Laboratory. The technology can be extended to other frequencies. Brief Description. In this research work ultra-high power solid-state radio frequency sources are proposed operating at the stated frequencies of interest. The approach employs high voltage Gallium Nitride radio frequency transistors, operating at 100 V or higher, to achieve 5-kilowatts continuous-wave and 10 kilowatts pulse power level in a small form factor. The 5 kilowatts building block reduces the required number of combiners and related losses to achieve megawatts power levels. The design employs harmonic tuning techniques as used in class E, F and inverse F power amplifiers to achieve >70% efficiency and assembly techniques that overcome heat dissipation in such high power density systems. Solid-state technology achieves million hour operating lifetime compared to 10 – 100 thousand hours for incumbent technology based on vacuum tubes. Additionally, the modular approach afforded by a solid-state solution avoids complete system shutdown when one module fails. Overall, the approach reduces capital and operating cost. Research Results. During Phase I radio frequency Gallium Nitride building block transistors with 50 mm gate periphery were designed and built which achieve ~600 W continuous-wave when operating at 100 V bias and 1-kW pulsed when operating at 150V. This level of performance has been demonstrated with operation at 325 and 650 MHz, and in both cases measured efficiency exceeded 70%. Potential Applications. The technology identified as suitable for high efficiency power sources in particle accelerators can also be applied in megawatt class radars and several industrial, scientific and medical applications such as microwave sintering, radio frequency and microwave ablation, oil percolation, MRI scanners and Nuclear Magnetic Resonance spectrometers, etc… The high efficiency of these devices also translates into reduced electrical power consumption and lower cost of operation.

100 VDC↗
DOE OSTI2025

Flux Channeling Induced Nanoconfinement and Enhancement of Microwaves Imaged by Rabi Oscillation Mapping

With rapid advances in qubit technologies, techniques for localizing, modulating, and measuring RF fields and their impact on qubit performance are of the utmost importance. Here, we demonstrate that flux-channeling from a permalloy nanowire can be used to achieve localized spatial modulation of an RF field and that the modulated field can be mapped with high resolution by using the Rabi oscillations of an NV center. Rabi maps reveal ∼100 mm wavelength microwaves concentrated in sub-300 nm regions with up to ∼16× power enhancement. This modulation is robust over a 20 dBm power range and has no adverse impact on NV T 2 coherence time. Micromagnetic simulations confirm that the modulated field results from the nanowire’s stray field through its constructive/destructive interference with the incident RF field. Our findings provide a new pathway for controlling qubits, amplifying RF signals, and mapping local fields in various on-chip RF technologies.

Diamond↗
DOE OSTI2017

Ordnance News

Since July of 2016 I have been assigned as a Guest Scientist at Los Alamos National Laboratory under the Training With Industries (TWI) Program. Los Alamos National Laboratory has proven to be a challenging and rewarding assignment in which I have found myself at the cutting edge of technologies pertinent to the Explosive Ordnance Disposal career field. In the last 7 months I have had the pleasure of working in an applications group that conducts research at the DOE “Q” and SCI levels. The group “uses a broad range of engineering and scientific expertise to support nuclear counter proliferation (NCP), nuclear counter terrorism (NCT), and nuclear emergency response (ER) missions. The Group contributes to national programs intended to protect, deter, and respond to weapons of mass destruction through tailored training and by using specialized applied electromagnetic solutions, rapid prototyping, designing/building/testing/delivering tools and trainers along with novel safing technologies, RF solutions, and cyberphysical applications”. While the specifics of the work performed are classified, the groups “core expertise includes pulsed power; EMP effects; nuclear weapons engineering; weapons effects and materials; predictive/hydrodynamic modeling and testing; firing and penalty systems; x-ray and non-destructive evaluation of threat devices; applied physics; advanced RF systems; powerline communications; novel electronics; 3-D printing of specialized components and cyber assessment/response technologies”. (int.lanl.gov/org/padgs/threat-identification-response/analytics-intelligencetechnology/ a-3/index.shtml)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

RF Frontiers for Particle Physics, the US View

In this talk I provide an update on the RF research for future colliders in the U.S., through the prism of Snowmass and P5 report. During Snowmass, we considered various applications of RF technology to the proposed future colliders and other accelerator- and non-accelerator-based experiments. P5 narrowed down the choices of future machines. The colliders include circular and linear $e^+ e^-$ Higgs factories, and longer-term options such as muon and hadron high energy colliders. I will start with Snowmass and P5 recommendations. As it is impossible to cover all possible RF R&D topics, I will discuss only three critical topics relevant to future colliders: efficiency of RF power sources, cold normal conducting RF, and cavities for ionization channel of muon collider. Progress on SRF accelerating cavities for future colliders will be covered in a separate talk. The choice of topics reflects my preference and in some cases ignorance, which I think is inevitable when one tries to cover such a broad subject.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Optimizing superconducting Nb film cavities by mitigating medium-field Q -slope through annealing

Niobium films are of interest in applications in various superconducting devices, such as superconducting radiofrequency cavities for particle accelerators and superconducting qubits for quantum computing. In this study, we address the persistent medium-field Q-slope issue in Nb film cavities, which, despite their high-quality factor at low RF fields, exhibit a significant Q-slope at medium RF fields compared to bulk Nb cavities. Traditional heat treatments, effective in reducing surface resistance and mitigating the Q-slope in bulk Nb cavities, are challenging for Nb-coated copper cavities. To overcome this challenge, we employed DC bias high-power impulse magnetron sputtering to deposit Nb film onto a 1.3 GHz single-cell elliptical bulk Nb cavity, followed by annealing treatments aimed at modifying the properties of the Nb film. In-situ annealing at 340 °C increased the quench field from 10.0 to 12.5 MV m −1 . Vacuum furnace annealing at 600 °C and 800 °C for 3 h resulted in a quench field increase of 13.5 and 15.3 MV m −1 , respectively. Further annealing at 800 °C for 6 h boosted the quench field to 17.5 MV m −1 . Additionally, the annealing treatments significantly reduced the field dependence of the surface resistance. However, increasing the annealing temperature to 900 °C induced a Q-switch phenomenon in the cavity. The analysis of RF performance and material characterization before and after annealing has provided critical insights into how the microstructure and impurity levels in Nb films influence the evolution of the Q-slope in Nb film cavities. Our findings highlight the significant roles of hydrides, high local misorientation, and lattice and surface defects in driving field-dependent losses. By strategically optimizing film properties and controlling impurity levels, we demonstrate a promising pathway to mitigate the medium-field Q-slope, paving the way for more efficient superconducting RF technologies.

Nb film↗
DOE OSTI2017

Phase space manipulations for optimization of an inverse free electron laser

The Inverse Free Electron Laser (IFEL) has developed into a mature advanced accelerator with the ability to produce mono energetic high brightness beams accelerated at gradients beyond those of conventional RF technology. By copropagating a relativistic electron beam and a high power laser in a strongly tapered undulator, resonant energy exchange can be maintained over large distances. To optimize the number of electrons accelerated in an IFEL, one must prepare the initial electron beam phase space such that a majority of particles are injected at the accelerating phase of the ponderomotive potential. We present a scheme for optimization of the Rubicon IFEL accelerator trapping by preparing the initial electron beam phase space. Utilizing two cascaded modulator-chicane pre-bunchers simulations predict 95% capture of the injected electron beam.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Design Considerations for Secure Wireless Sensor Communication Systems in Harsh Electromagnetic Environments of Nuclear Reactor Facilities

Wireless sensors can potentially play a significant role in safety, efficiency, and reliability of the instrumentation and control process in current and next generation nuclear power reactors. While conventional narrowband wireless sensors have shown a certain level of success in some nuclear power plants (NPPs), the radio frequency (RF) propagation challenges posed by the heavy metallic and cluttered environment of NPPs has prevented their widespread use in such operations. Furthermore, these challenges include RF wave propagation in harsh (reflective, absorptive, cluttered) environments, data security issues, and RF interference to and from other devices in the vicinity of a nuclear reactor core. In this paper, first we address how ultrawideband (UWB) RF technology can complement the narrowband (i.e., WiFi) solutions that have been used in some NPPs by providing an alternative solution in addressing the signal propagation issues in such electromagnetically harsh environments. Second, we discuss and present the UWB software simulation results on multipath harsh environments, and then address the data security issues. In the final sections of the paper, we present the experimental results of using UWB signaling in a representative harsh environment conducted at the Massachusetts Institute of Technology research reactor site. We plan to develop the UWB communications hardware based on the results of this paper and report on its performance in the field with emphasis on the security aspects of the system in a subsequent paper.

42 ENGINEERING↗
DOE OSTI2023

An 8 GeV linac as the Booster replacement in the Fermilab Power Upgrade

Increasing the Main Injector beam power above ~ 1.2 MW requires replacement of the 8 GeV Booster by a higher intensity alternative. In this paper, we consider an 8 GeV linac Booster replacement that produces 8 GeV H$^{-}$ beam for injection into the Recycler Ring or Main Injector. This upgrade will maximize the beam available for neutrino production for the long baseline DUNE experiment to greater than 2.5 MW and enable a next generation frontier experiments. The 8 GeV linac takes ~ 1 GeV beam from the PIP-II Linac and accelerates it to ~ 2 GeV in a650 MHz superconducting RF linac, followed by a ~ 2 to 8 GeV pulsed linac using 1300 MHz cryomodules. The linac components incorporate recent improvements in superconducting RF technology. The linac configuration and beam dynamics requirements are presented. Injection options are discussed, including use of an8 GeV Accumulator Ring. Foil-based injection is the present standard but R&D toward implementing laser-assisted injection could enable a significant improvement. Research needed to implement the Booster replacement is described.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Higher order mode analysis of a 915 MHz 2-cell cavity for a prototype industrial accelerator

A possible solution to reduce the complexity posed by the cryogenic systems in a superconducting RF accelerator for industrial applications, is to capitalize on the advances achieved by the Nb3Sn superconducting RF technology, as well as the feasibility of a reliable 4 K cooling system, based on commercial cryocoolers. Following this philosophy, the conceptual design for a prototype, conduction-cooled, 4 MeV, 20 kW SRF electron linac, is being developed at Jefferson Lab. Such design is based on a 915 MHz two-cell Nb3Sn cavity. In this contribution, we present the proposed cavity design, including the fundamental power coupler, and the analysis of the Higher Order Modes, using numerical simulations to estimate the potentially dangerous modes and to provide the requirements for damping for reliable operations with a cryocooler.

Rimmer, Robert↗