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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Ancho Canyon RF Collect, March 2, 2017: Final Report

We report the results from the March 2, 2017, Ancho Canyon RF collection. While bright electromagnetic signals were seen nearby the firing point, there were no detections of signals from the explosively-fired fuse at a collection point about 570m distant on the East Mesa. However, "liveness" tests of the East Mesa data acquisition system and checks of the timing both suggest that the collection system was working correctly. We examine possible reasons for the lack of detection. Principal among these is that the impulsive signal may be small compared to the radio frequency background on the East Mesa.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

June 2017 Ancho Canyon RF Collects: Final Report

We report the results from the June 8, 2017, Ancho Canyon RF collection. While bright, electromagnetic signals were seen close to the firing point, there were no detections of signals from the explosively-fired fuse (EFF) at a collection point about 600m distant on the East Mesa. The East Mesa site was unable to collect data because the uninterruptible power supply (UPS) was exhausted by the time of the shot. We did see signals from the EFF at the Bunker 57 antennas, about 123m distant from the Point 88 firing point. The strength of these signals is consistent with our limited knowledge of the collection antenna performance and the use of the standard model to predict the electric field strength. From our knowledge of the geometry of the EFF loop and the current in the loop in this test, and from measurements at the Bunker 57 site, we predict that we would have seen signals of about 50mV at 3.67MHz in a 100 kHz channel on the Rohde & Schwarz HE010 antennas at the East Mesa location. The noise oor there is about 0.113mV (based on the March 2017 collects). Thus we would have had an SNR of 53 dB from the collect, had the data collection system been running.

58 GEOSCIENCES↗
DOE OSTI2017

A Thin Lens Model for Charged-Particle RF Accelerating Gaps

Presented is a thin-lens model for an RF accelerating gap that considers general axial fields without energy dependence or other a priori assumptions. Both the cosine and sine transit time factors (i.e., Fourier transforms) are required plus two additional functions; the Hilbert transforms the transit-time factors. The combination yields a complex-valued Hamiltonian rotating in the complex plane with synchronous phase. Using Hamiltonians the phase and energy gains are computed independently in the pre-gap and post-gap regions then aligned using the asymptotic values of wave number. Derivations of these results are outlined, examples are shown, and simulations with the model are presented.

43 PARTICLE ACCELERATORS↗
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 OSTI2014

Processing and cryogenic RF testing of PKU-4C-1206

PKU-4C-1206 is a 4-cell 1.3GHz cavity manufactured by Peking University. It was processed and cryogenically RF tested at Jefferson Lab under cooperative research and development agreement (CRADA, No. JSA2013S011).

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

High Brightness Superconducting RF Gun Cavity

The Phase I goals were to numerically optimize a TM020/TM010 SRF gun with a demountable back wall, using SLAC’s state-of-the-art massive parallel ACE3P suite of 3D Finite Element Analysis codes available at the National Energy Research Scientific Computing Center (NERSC) , which includes: a) TM020 cell shape, including impact of RF focusing on beam dynamics; b) optimum number of TM010-cells to achieve low emittances; c) multipacting simulations back wall opening; d) dark current investigations; e) studies on LOM and HOM damping with waveguides/port on TM020-cells using wakefield solver can be conducted as well but are not required stringently; f) conceptual design of a power input coupler; g) multiphysics simulations to optimize the gun thermal management and cooling requirements for a superconducting joint; h) multivariate beam dynamical optimization in conjunction with the gun optimization; and i) finalize an engineering design for vertical high power tests at JLab.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Analysis of Coupled Bunch Instabilities in the NSLS-II Storage Ring with a 7-cell PETRA-III RF Structure

We studied the coupled-bunch instability driven by a 7-cell PETRA-III cavity structure, which is considered to be installed in the commissioning Phase 1 in the NSLS-II storage ring at an average current of 25mA. For instability threshold calculations we used the parameters of the bare lattice (no DW’s and Landau cavities). The transverse and longitudinal coupled-bunch instabilities can be driven by the higher order modes (HOM’s) of the 7-cell PETRA-III cavity structure. In the case of uniform filling the beam is longitudinally stable, and transversely unstable at zero chromaticity. To increase the transverse instability threshold we studied the stabilizing effect of the slow head-tail instability at positive chromaticity. We assume the slow head tail effect is driven by a broadband resonator impedance. In the case of all RF buckets filled (M=1320 bunches, N=3.1x10 8 particles per bunch) the beam is unstable for values of the chromaticity in the range [0 2]. To increase the damping provided by the slow head-tail effect, we discuss fillings with a larger number of particles per bunch. We analyze uniform filling configurations with M=132 (N=3.1x10 9 ) and M=66 (N=6.2x10 9 ). We also discussed HOM’s frequencies detuning based upon temperature change as a cure of the coupled-bunch instabilities, and proposed working points to make the 7-cell PETRA-III cavity structure stable under coupled-bunch interaction.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Low RF Power Plasma Ignition and Detection for In-Situ Cleaning of 1.3 GHz 9-Cell Cavities

Superconducting Radio Frequency (SRF) cavities performance preservation is crucial, from vertical test to accelerator operation. Field Emission (FE) is still one of the performance limiting factors to overcome and plasma cleaning has been proven successful by the Spallation Neutron Source (SNS), in cleaning field emitters and increasing the work function of Nb. A collaboration has been established between Fermi National Accelerator Laboratory (FNAL), SLAC National Accelerator Lab- oratory and Oak Ridge National Laboratory (ORNL) with the purpose of applying plasma processing to the Linac Coherent Light Source-II (LCLS-II) cavities, in order to minimize and overcome field emission without affecting the high Q of nitrogen-doped cavities. The cleaning for LCLS-II will follow the same plasma composition adopted at SNS, which allows in-situ processing of cavities installed in cryomod-ules from hydrocarbon contaminants. A novel method for plasma ignition has been developed at FNAL: a plasma glow discharge is ignited using high order modes to overcome limitations imposed by the fundamental power coupler, allowing in-situ cleaning for cavities in cryomodule. The plasma can be easily ignited and tuned in each of the cavity cells using low RF power. A method for plasma detection has been developed as well, which allows the detection of the plasma location in the cavity without the need of cameras at both cavity ends. The presented method can be applied to other multi-cell cavity designs, even for accelerators where the coupling for the fundamental modes at room temperature is very weak.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Cryogenic RF tests of US LARP DQW SPS-series cavities

Crab cavities are one of the several components included in the luminosity upgrade of the Large Hadron Collider (HL-LHC). For nominal operation, the cavities have to provide a nominal deflecting kick of 3.4 MV per cavity in Continuous Wave operation at 2 K. The requirement for an unjacketed cavity – bare cavity equipped with Higher-Order Mode (HOM) filters and field antenna – is to reach at least a deflecting voltage of 4.1 MV (20% margin) with the heat load to the 2 K bath below 10 W. Cryogenic RF tests confirmed the required performances in bare cavities, with several cavities exceeding the required voltage by more than 50%. However, the first tests of a Double-Quarter Wave (DQW) cavity with one out of three HOM filters did not reach the required voltage. The present paper describes the studies and tests conducted to understand the limiting factor in the operation of a DQW cavity with HOM filters in the most up-to-date prototypes produced in the US and based on the DQW SPS-series design. The recipe to meet the performance specification for a bare DQW cavity with HOM filters and exceed the voltage requirement by more than 35% is discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Radiofrequency Accelerator R&D Strategy Report: DOE HEP General Accelerator R&D RF Research Roadmap Workshop, March 8-9, 2017

Over a two-day period, March 8-9, 2017 the Office of High Energy Physics convened a workshop in Gaithersburg, MD to seek community input on development of a radiofrequency (RF) research ten-year roadmap to guide the General Accelerator Research and Development Program (GARD). As described in the charge, the roadmap should reflect the Particle Physics Project Prioritization Panel strategy and the subsequent HEPAP Accelerator Subpanel recommendations. The charge for the workshop can be found in Appendix A. At the workshop, proponents of superconducting radiofrequency technology (SRF) and normal conducting radiofrequency technology (NCRF), along with invited university and laboratory experts, critically discussed opportunities, gaps, and requirements relevant to the development of a roadmap. The roadmap workshop was preceded by preparatory workshops at SLAC on NCRF and Fermilab on SRF.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

A Medium Frequency RF Sensor for Detection of Magnetized Quark Nuggets

It is hypothesized that dark matter is composed of particles called quark nuggets, and further that these particles have a permanent magnetic dipole moment. If this hypothesis is true, calculations predict that a magnetized quark nugget (MQN) will oscillate when encountering the Earth's magnetosphere, and emit RF radiation between 30kHz and 30MHz. To support testing this hypothesis, a loop antenna sensor was designed and developed, which is described in this report. This sensor operates between 300kHz and 3MHz and achieves about -11dBfT/vHz sensitivity at 1.5MHz.

42 ENGINEERING↗
DOE OSTI2022

EMITTANCE GROWTH DUE TO RF PHASE NOISE IN CRAB CAVITIES

The Electron-Ion Collider (EIC) incorporates beam crabbing to recover geometric luminosity loss from the nonzero crossing angle at the interaction point (IP). It is well-known that crab cavity imperfections can cause growth of colliding beam emittances, thus degrading collider performance. Here we report a particle tracking study to quantify these effects. Presently the study is focused on crab cavity RF phase noise. Simulations were carried out using Bmad. Dependence of emittance growth on phase noise level was obtained which could be used for developing crab cavity phase control specifications. We also benchmarked these simulations with theory.

Huang, H.↗