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Krstic PS, Dwivedi S, Ostrowski ET, Abe S, Maan A, van Duin ACT, Koel BE. Hydrogen irradiation-driven computational surface chemistry of lithium oxide and hydroxide. J Chem Phys 2023; 159:244703. [PMID: 38153149 DOI: 10.1063/5.0177460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 12/04/2023] [Indexed: 12/29/2023] Open
Abstract
We have investigated, using molecular dynamics, the surface chemistry of hydrogen incident on the amorphous and crystalline lithium oxide and lithium hydroxide surfaces upon being slowed down by a collision cascade and retained in the amorphous surface of either Li2O or LiOH. We looked for the bonding of H to the resident structures in the surface to understand a possible chain of chemical reactions that can lead to surface transformation upon H atom impact. Our findings, using Density-Functional Theory (DFT) trained ReaxFF force field/electronegativity equalization method potentials, stress the importance of inclusion of polarization in the dynamics of a Li-O-H system, which is also illustrated by DFT energy minimization and quantum-classical molecular dynamics using tight binding DFT. The resulting polar-covalent chemistry of the studied systems is complex and very sensitive to the instantaneous positions of all atoms as well as the ratio of concentrations of various resident atoms in the surface.
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Affiliation(s)
- P S Krstic
- TheoretiK, Port Jefferson Station, New York 11776, USA
- Stony Brook University, Stony Brook, New York 11749, USA
| | - S Dwivedi
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - E T Ostrowski
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - S Abe
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - A Maan
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - A C T van Duin
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - B E Koel
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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2
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Maan A, Boyle D, Majeski R, Banerjee S, Franscisquez M, Kaita R, Wilkie G, Capecchi W, Kubota S, Hansen C, Soukhanovskii V. Improved neutral and plasma density control with increasing lithium wall coatings in the Lithium Tokamak Experiment- β (LTX- β ). NUCLEAR MATERIALS AND ENERGY 2023. [DOI: 10.1016/j.nme.2023.101408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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3
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Banerjee S, Boyle DP, Maan A, Majeski R, Kaita R, Smith D, von Hellermann M, Hansen C, Capecchi W, Elliott D. Feasibility study of a high spatial and time resolution beam emission spectroscopy diagnostic for localized density fluctuation measurements in Lithium Tokamak eXperiment-β (LTX-β). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:113523. [PMID: 36461475 DOI: 10.1063/5.0101834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 09/28/2022] [Indexed: 06/17/2023]
Abstract
Trapped electron mode (TEM) is the main source of turbulence predicted for the unique operation regime of a flat temperature profile under low-recycling conditions in the LTX-β tokamak, while ion temperature gradient driven turbulence may also occur with gas fueling from the edge. To investigate mainly TEM scale density fluctuations, a high spatial and time resolution 2D beam emission spectroscopy (BES) diagnostic is being developed. Apart from spatially localized density turbulence measurement, BES can provide turbulence flow and flow shear dynamics. This BES system will be realized using an avalanche photodiode-based camera and narrow band interference filter. The system can acquire data at 2 MHz. Simulations with the Simulation of Spectra (SOS) code indicate that a high signal to noise ratio can be achieved with the proposed system. This will enable sampling the density fluctuations at this high time resolution. The design considerations and system optimization using the SOS code are presented.
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Affiliation(s)
- Santanu Banerjee
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - D P Boyle
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - A Maan
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - R Majeski
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - R Kaita
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - D Smith
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - M von Hellermann
- Institute for Energy and Climate Research IEK-4, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - C Hansen
- Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195, USA
| | - W Capecchi
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - D Elliott
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
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4
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Failure of a lithium-filled target and some implications for fusion components. FUSION ENGINEERING AND DESIGN 2021. [DOI: 10.1016/j.fusengdes.2021.112664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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Kafle N, Elliott D, Garren EW, He Z, Gebhart TE, Zhang Z, Biewer TM. Design and implementation of a portable diagnostic system for Thomson scattering and optical emission spectroscopy measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:063002. [PMID: 34243554 DOI: 10.1063/5.0043818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 05/18/2021] [Indexed: 06/13/2023]
Abstract
A diagnostic system, which has a design goal of high-portability, has been designed at Oak Ridge National Laboratory (ORNL). This project aims at providing measurements of key plasma parameters (ne, Te, ni, Ti) for fusion-relevant devices, utilizing Thomson scattering (TS) and optical emission spectroscopy (OES). The innovative design employs mostly commercial off-the-shelf instrumentation and a traveling team of researchers to conduct measurements at various magnetic-confinement plasma devices. The TS diagnostic uses a Quantel Q-smart 1500 Nd:YAG laser with a 2ω harmonic generator to produce up to 850 mJ of 532 nm laser pulses at 10 Hz. Collection optics placed at the detection port consists of an 11 × 3 optical fiber bundle, where the TS diagnostic uses an 11 × 1 subset array of the fibers, the OES diagnostic uses another 11 fibers, and the remaining fibers are available to the host institution. The detection system is comprised of two separate IsoPlane-320 spectrometers with triple-grating turrets of various line spacing and two PI-MAX 4 intensified CCD detectors, used simultaneously to measure a broad range of ion, impurity, and electron parameters. The self-contained diagnostic package also includes a data processing and storage system. The design and initial implementation of the TS-OES diagnostic system are described. The experiments from the proof-of-principle operation of the portable package on a high density (∼2.5 × 1022 m-3) and low-temperature (∼5 eV) electrothermal arc source at ORNL are also discussed.
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Affiliation(s)
- N Kafle
- Oak Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - D Elliott
- Oak Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - E W Garren
- Oak Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Z He
- University of Tennessee-Knoxville, Knoxville, Tennessee 37996, USA
| | - T E Gebhart
- Oak Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Z Zhang
- University of Tennessee-Knoxville, Knoxville, Tennessee 37996, USA
| | - T M Biewer
- Oak Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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7
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Maan A, Kaita R, Ostrowski ET, Majeski R, Boyle DP, Donovan DC, Ellis RA, Koel BE, Biewer TM. A simple vacuum suitcase for enabling plasma facing component characterization in fusion devices. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:026104. [PMID: 32113407 DOI: 10.1063/1.5119166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/18/2020] [Indexed: 06/10/2023]
Abstract
We have demonstrated a vacuum suitcase to transport samples in vacuo to a surface analysis station for characterization of tokamak plasma facing components (PFCs). This technique enables surface analysis at powerful, dedicated stations that are not encumbered by design constraints imposed on them by a tokamak. The vacuum suitcase is an alternative solution to characterizing PFCs using diagnostics that are designed and built around a tokamak. The vacuum suitcase, called the Sample Exposure Probe (SEP), features mobile ultra-high vacuum pumping. Active pumping under high vacuum enables sample transfer between the Lithium Tokamak eXperiment-β (LTX-β) and a high resolution X-ray Photoelectron Spectroscopy (XPS) system that is situated close by. A thermocouple inserted in the back of the sample head measures heat flux from the plasma during exposure, and together with a button heater, allows the sample to match the LTX-β PFCs in high temperature operations. As vacuum conditions are better during transfer and analysis than in the tokamak, less contamination is introduced to the samples. XPS scans on a dedicated analysis station enable peak identification due to higher resolution and signal to noise ratio. A similar probe could be implemented for other fusion devices. The SEP is the first vacuum suitcase implementation for fusion applications that incorporates active pumping.
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Affiliation(s)
- A Maan
- Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37796, USA
| | - R Kaita
- Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37796, USA
| | - E T Ostrowski
- Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - R Majeski
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - D P Boyle
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - D C Donovan
- Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37796, USA
| | - R A Ellis
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - B E Koel
- Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - T M Biewer
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
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Constraints on conceptual design of diagnostics for the high magnetic field COMPASS-U tokamak with hot walls. FUSION ENGINEERING AND DESIGN 2019. [DOI: 10.1016/j.fusengdes.2019.03.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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Zhang X, Elliott D, Maan A, Boyle D, Kaita R, Majeski R. Design and calibration of a retarding field energy analyzer for the LTX-β scrape off layer and modeling of electrostatic potential in a collisionless SOL. NUCLEAR MATERIALS AND ENERGY 2019. [DOI: 10.1016/j.nme.2019.02.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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10
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Campanell MD, Johnson GR. Thermionic Cooling of the Target Plasma to a Sub-eV Temperature. PHYSICAL REVIEW LETTERS 2019; 122:015003. [PMID: 31012647 DOI: 10.1103/physrevlett.122.015003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/27/2018] [Indexed: 06/09/2023]
Abstract
Contemporary models of bounded plasmas assume that the target plasma electron temperature far exceeds the temperature of the cold electrons emitted from the target, T_{emit}. We show that when the sheath facing a collisional plasma becomes inverted, the target plasma electron temperature has to equal T_{emit} even if the upstream plasma is hotter by orders of magnitude. This extreme cooling effect can alter the plasma properties and the heat transmission to thermionically emitting surfaces in many applications. It also opens a possibility of using thermionic divertor plates to induce detachment in tokamaks.
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Affiliation(s)
- M D Campanell
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - G R Johnson
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
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11
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Kubota S, Majeski R, Boyle DP, Kaita R, Kozub T, Lantsov R, Merino E, Nguyen XV, Peebles WA, Rhodes TL. Millimeter-wave interferometry and far-forward scattering for density fluctuation measurements on LTX- β. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10H114. [PMID: 30399948 DOI: 10.1063/1.5039418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 06/19/2018] [Indexed: 06/08/2023]
Abstract
The λ ≈ 1 mm (f = 288 GHz) interferometer for the Lithium Tokamak Experiment-β (LTX-β) will use a chirped-frequency source and a centerstack-mounted retro-reflector mirror to provide electron line density measurements along a single radial chord at the midplane. The interferometer is unique in the use of a single source (narrow-band chirped-frequency interferometry) and a single beam splitter for separating and recombining the probe and reference beams. The current work provides a documentation of the interferometry hardware and evaluates the capabilities of the system as a far-forward collective scattering diagnostic. As such, the current optical setup is estimated to have a detection range of 0.4 ≲ k ⊥ ≲ 1.7 cm-1, while an improved layout will extend the upper k ⊥ limit to ∼3 cm-1. Measurements with the diagnostic on LTX are presented, showing interferometry results and scattered signal data. These diagnostics are expected to provide routine measurements on LTX-β for high frequency coherent density oscillations (e.g., Alfvénic modes during neutral beam injection) as well as for broadband turbulence.
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Affiliation(s)
- S Kubota
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - R Majeski
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - D P Boyle
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R Kaita
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - T Kozub
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R Lantsov
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - E Merino
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - X V Nguyen
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - W A Peebles
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - T L Rhodes
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
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12
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Elliott DB, Biewer TM, Boyle DP, Kaita R, Majeski R. The charge exchange recombination spectroscopy diagnostic on the upgraded Lithium Tokamak eXperiment (LTX- β). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10D118. [PMID: 30399896 DOI: 10.1063/1.5039368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 08/29/2018] [Indexed: 06/08/2023]
Abstract
The Lithium Tokamak eXperiment has undergone an upgrade to LTX-β, a major part of which is the addition of neutral beam injection (NBI). NBI has allowed for a new charge exchange recombination spectroscopy (CHERS) system to be installed in order to measure impurity concentrations, ion temperature, and toroidal velocity. Previously on LTX measuring these parameters relied on passive spectroscopy and inversion techniques and had large uncertainty. The CHERS system has 52 total views, split into four groups of 13, half facing toward the beam and half symmetrically facing away from the beam, so the background non-beam related emission can be simultaneously subtracted. Both sets of views sample a major radius of 27-59 cm, with resolution through the beam of 1.5-2.5 cm. LTX-β is expected to have its magnetic axis near 35 cm, with minor radii of 18-23 cm. Three separate spectrometers will be used for the diagnostic, giving the system great flexibility to simultaneously measure emission from multiple impurity lines. The viewing optics are f/1.8, allowing all of the spectrometers to be fully illuminated. Design and calibration of the system as well as the advantages of various configurations of the spectrometers will be highlighted.
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Affiliation(s)
- D B Elliott
- Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6169, USA
| | - T M Biewer
- Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6169, USA
| | - D P Boyle
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543, USA
| | - R Kaita
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543, USA
| | - R Majeski
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543, USA
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Hughes PE, Majeski R, Kaita R, Kozub T, Hansen C, Boyle DP. Magnetic perturbation diagnostics in the high-temperature lithiated environment of LTX- β. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10J104. [PMID: 30399897 DOI: 10.1063/1.5035359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Magnetic perturbation measurements will be invaluable for characterizing Lithium Tokamak Experiment Beta (LTX-β) plasmas due to the time-evolving 3D nature of the magnetic fields generated by eddy currents in the vessel and copper shell segments, as well as enhanced MHD instability drive due to newly introduced neutral beam heating. The LTX-β upgrade includes two new arrays of Mirnov coils: a shell eddy sensor array of two-axis coils distributed over the back surface of one shell segment and a toroidal array of poloidal field coils at the low-field side midplane gap. Evaporative lithium wall-coating and the high temperatures required for liquid lithium wall operation both complicate the implementation of in-vessel diagnostics. While the shell array is protected from lithium exposure, the shell segment to which it is mounted will at times exceed 300 °C. The toroidal array, however, will experience direct line-of-sight exposure to the lithium evaporator as well as close proximity to the hot shell and may also be subject to poorly confined beam-driven fast ions. We describe how the two new Mirnov coil arrays meet these environmental challenges and enhance the LTX-β diagnostic suite.
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Affiliation(s)
- P E Hughes
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R Majeski
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R Kaita
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - T Kozub
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - C Hansen
- Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195, USA
| | - D P Boyle
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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Zuo GZ, Hu JS, Maingi R, Yang QX, Sun Z, Huang M, Chen Y, Yuan XL, Meng XC, Xu W, Gentile C, Carpe A, Diallo A, Lunsford R, Mansfield D, Osborne T, Tritz K, Li JG. Upgraded flowing liquid lithium limiter for improving Li coverage uniformity and erosion resistance in EAST device. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:123506. [PMID: 29289198 DOI: 10.1063/1.4997806] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on design and technology improvements for a flowing liquid lithium (FLiLi) limiter inserted into auxiliary heated discharges in the experimental advanced superconducting tokamak device. In order to enhance Li coverage uniformity and erosion resistance, a new liquid Li distributor with homogenous channels was implemented. In addition, two independent electromagnetic pumps and a new horizontal capillary structure contributed to an improvement in the observed Li flow uniformity (from 30% in the previous FLiLi design to >80% in this FLiLi design). To improve limiter surface erosion resistance, hot isostatic press technology was applied, which improved the thermal contact between thin stainless steel protective layers covering the Cu heat sink. The thickness of the stainless steel layer was increased from 0.1 mm to 0.5 mm, which also helped macroscopic erosion resilience. Despite the high auxiliary heating power up to 4.5 MW, no Li bursts were recorded from FLiLi, underscoring the improved performance of this new design.
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Affiliation(s)
- G Z Zuo
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - J S Hu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - R Maingi
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - Q X Yang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Z Sun
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - M Huang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Y Chen
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - X L Yuan
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - X C Meng
- Department of Applied Physics, Hunan University, Changsha 410082, China
| | - W Xu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - C Gentile
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - A Carpe
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - A Diallo
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - R Lunsford
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - D Mansfield
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - T Osborne
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - K Tritz
- Johns Hopkins University, Baltimore, Maryland 21211, USA
| | - J G Li
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China
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