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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Characterization of W production during ICRF operations: experiments and modeling

For successfully heating plasma with waves in the ion cyclotron range of frequencies (ICRFs), mitigating impurity production is just as crucial as maximizing power coupling, especially in high-Z environments. ICRF can effectively deposit energy on ions, modify turbulence-driven transport, and enhance fusion reaction efficiency, but only when its power coupling has minimal impact on impurity production. To do so, one must rely on a toroidal array of at least three active elements excited with appropriate phasing and power ratio to reduce the currents induced on the antenna frame below levels critical for physical sputtering. In contrast to classic two-strap antennas, which are optimized for dipole phasing with equal power on both straps, three-strap antennas in ASDEX Upgrade (AUG)—but also four-strap antennas in JET, Alcator C-Mod, SPARC and ITER—offer the possibility to act also on the power ratio between the central and outer straps. With optimal settings, impurity production can be reduced substantially, making the ICRF compatible with the high-Z wall. This paper explores the characteristics of the AUG three-strap antennas in terms of impurity production, as well as the key role of plasma composition in this process. Numerical simulations were performed using SSWICH and Petra-M (finite element codes) to quantify impurity production and compare with experimental results. Energies of ions falling on antenna limiters (measured with probes) are well predicted by both codes. These tools are then used to further describe the source of the impurity, namely the gross erosion of tungsten from an ICRF antenna, for different plasma mixtures. Results are also compared to spectroscopy data. Ultimately, we show that deleterious effects of the ICRF on plasma surface interactions will be weaker in plasmas containing larger fractions of highly ionized heavier low-Z impurity, which is typically relevant for experiments relying on impurity seeding.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Operational Experience With the GEM Detector Assembly Lines for the CMS Forward Muon Upgrade

The CMS Collaboration has been creating large-area triple-gas electron multiplier (GEM) detectors to be installed in the muon Endcap regions of the CMS experiment in 2019 to maintain forward muon trigger and tracking performance at the High-Luminosity upgrade of the Large Hadron Collider (LHC); 10 preproduction detectors were built at CERN to commission the first assembly line and the quality controls (QCs). These were installed in the CMS detector in early 2017 and participated in the 2017 LHC run. The collaboration has prepared several additional assembly and QC lines for distributed mass production of 160 GEM detectors at various sites worldwide. In 2017, these additional production sites have optimized construction techniques and QC procedures and validated them against common specifications by constructing additional preproduction detectors. Using the specific experience from one production site as an example, we report on how the QCs make use of independent hardware and trained personnel to ensure fast and reliable production. Preliminary results on the construction status of CMS GEM detectors are presented with details of the assembly sites involvement.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

OPERATIONAL EXPERIENCE WITH FAST FIBER-OPTIC BEAM LOSS MONITORS FOR THE ADVANCED PHOTON SOURCE STORAGE RING SUPERCONDUCTING UNDULATORS

Fast fiber-optic (FFO) beam loss monitors (BLMs) installed with the first two superconducting undulators (SCUs) in the Advanced Photon Source storage ring have proven to be a useful diagnostic for measuring deposited charge (energy) during rapid beam loss events. The first set of FFOBLMs were installed outside the cryostat of the short SCU, a 0.33-m long device, above and below the beam centerline. The second set are mounted with the first 1.1-mlong SCU within the cryostat, on the outboard and inboard sides of the vacuum chamber. The next 1.1-m-long SCU is scheduled to replace the short SCU later in 2016 and will be fitted with FFOBLMs in a manner similar to original 1.1-m device. The FFOBLMs were employed to set timing and voltage for the abort kicker (AK) system. The AK helps to prevent quenching of the SCUs during beam dumps [1] by directing the beam away from the SC magnet windings. The AK is triggered by the Machine Protection System (MPS). In cases when the AK fails to prevent quenching, the FFOBLMs show that losses often begin before detection by the MPS.

Dooling, J.↗
DOE OSTI2022

Operational Experience of the New Booster Cryomodule at the Upgraded Injector Test Facility

Since the early 1990s, the in­jec­tor of the CEBAF ac­cel­er­a­tor at Jef­fer­son Lab has re­lied on a nor­mal-con­duct­ing RF graded-beta cap­ture sec­tion to boost the ki­netic en­ergy of the elec­tron beam from 100 / 130 keV to 600 keV for sub­se­quent ac­cel­er­a­tion using a cry­omod­ule hous­ing two su­per­con­duct­ing 5-cell cav­i­ties sim­i­lar to those used through­out the ac­cel­er­a­tor. To sim­plify the in­jec­tor de­sign and im­prove the beam qual­ity, the nor­mal-con­duct­ing RF cap­ture sec­tion and the cry­omod­ule will be re­placed with a new sin­gle booster cry­omod­ule em­ploy­ing a su­per­con­duct­ing, β = 0.6, 2-cell-cav­ity cap­ture sec­tion and a sin­gle, β = 0.97, 7-cell cav­ity. The Up­graded In­jec­tor Test Fa­cil­ity at Jef­fer­son Lab is cur­rently host­ing the new cry­omod­ule to eval­u­ate its per­for­mance with beam be­fore in­stal­la­tion at CEBAF. While demon­strat­ing sat­is­fac­tory per­for­mance of the booster and good agree­ment with sim­u­la­tions, our beam test re­sults also speak to lim­i­ta­tions of ac­cel­er­a­tor op­er­a­tions in a noisy, ther­mally un­reg­u­lated en­vi­ron­ment.

Bruker, M. W.↗
DOE OSTI2023

Start-up Operation Experience with a Liquid Fluoride Salt Forced Convection Loop

A liquid fluoride salt forced convection test loop was constructed at Oak Ridge National Laboratory. Its unique features include a pebble bed test section, high-temperature instrumentation, a noncontact rotating gas seal for the pump, a silicon carbide flow tube, and a unique inductive heating technique. Initial startup and shake-down testing has been completed. This paper describes how several of the systems performed, highlights those that worked well, and discusses issues that arose during the start-up process. This discussion should be of interest to those who intend to develop molten salt technologies and who are interested in some of the specific techniques used in this experiment.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2022

Operational Experience of the New Booster Cryomodule at the Upgraded Injector Test Facility

Since the early 1990s, the in­jec­tor of the CEBAF ac­cel­er­a­tor at Jef­fer­son Lab has re­lied on a nor­mal-con­duct­ing RF graded-beta cap­ture sec­tion to boost the ki­netic en­ergy of the elec­tron beam from 100 / 130 keV to 600 keV for sub­se­quent ac­cel­er­a­tion using a cry­omod­ule hous­ing two su­per­con­duct­ing 5-cell cav­i­ties sim­i­lar to those used through­out the ac­cel­er­a­tor. To sim­plify the in­jec­tor de­sign and im­prove the beam qual­ity, the nor­mal-con­duct­ing RF cap­ture sec­tion and the cry­omod­ule will be re­placed with a new sin­gle booster cry­omod­ule em­ploy­ing a su­per­con­duct­ing, β = 0.6, 2-cell-cav­ity cap­ture sec­tion and a sin­gle, β = 0.97, 7-cell cav­ity. The Up­graded In­jec­tor Test Fa­cil­ity at Jef­fer­son Lab is cur­rently host­ing the new cry­omod­ule to eval­u­ate its per­for­mance with beam be­fore in­stal­la­tion at CEBAF. While demon­strat­ing sat­is­fac­tory per­for­mance of the booster and good agree­ment with sim­u­la­tions, our beam test re­sults also speak to lim­i­ta­tions of ac­cel­er­a­tor op­er­a­tions in a noisy, ther­mally un­reg­u­lated en­vi­ron­ment.

Bruker, M. W.↗
DOE OSTI2025

Operational Experience of the NML Cryogenic Plant at the FAST Test Facility

The New Muon Laboratory (NML) cools two individually cryostated superconducting radio frequency (SRF) capture cavities (CC) and one prototype ILC cryomodule (CM) with eight SRF cavities. This complex accelerates electrons at 150 MeV for the Integrable Optics Test Accelerator (IOTA) ring, located at the Fermilab Accelerator Science and Technology (FAST) facility. Since 2019, this R&D accelerator complex has gone through four science runs.

Wallace, T. [Fermilab]↗