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Bedoya F, Woller KB, Whyte DG. Study of the properties of thin Li films and their relationship with He plasmas using ion beam analysis in the DIONISOS experiment. Rev Sci Instrum 2018; 89:10J106. [PMID: 30399747 DOI: 10.1063/1.5034240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Plasma facing component (PFC) conditioning dramatically affects plasma performance in magnetic confinement fusion experiments. Lithium (Li) has been used in several machines to condition PFC with subsequent improvements to plasma performance. Multiple studies have investigated the interactions of Li with deuterium (D) and oxygen (O) in order to ascertain the mechanisms behind the enhanced plasma performance. Ion Beam Analysis (IBA) is a useful tool to interrogate PFC surfaces as they interact with plasmas. Dynamics of ion implantation and sputtering of surfaces (DIONISOS) is a linear plasma device, capable of generating discharges with fluxes ∼1021 m-2 s-1 and Te ∼6 eV, coupled to an ion accelerator. DIONISOS is capable of analyzing samples using Elastic Recoil Detection (ERD) and Rutherford Backscattering Spectroscopy (RBS) during plasma exposures. The facility has been equipped with a Li deposition system for evaporation of thin coatings on different substrates. The evaporator enables real time ERD and RBS measurements of deposition and erosion of Li coatings on different substrates and the interaction of the Li with the vacuum and plasma. Considerations for ERD, e.g., ion species, energy, and data acquisition frequency, are presented. This work is the basis for further investigation of He, H, and D retention in solid and liquid Li.
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Affiliation(s)
- F Bedoya
- MIT Plasma Science and Fusion Center, 175 Albany St., Cambridge, Massachusetts 02139, USA
| | - K B Woller
- MIT Plasma Science and Fusion Center, 175 Albany St., Cambridge, Massachusetts 02139, USA
| | - D G Whyte
- MIT Plasma Science and Fusion Center, 175 Albany St., Cambridge, Massachusetts 02139, USA
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Whyte DG. Plasma-Surface Interaction Studies on DIII-D and Their Implications for Next-Step Fusion Experiments. Fusion Science and Technology 2017. [DOI: 10.13182/fst05-a1063] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- D. G. Whyte
- University of Wisconsin, Madison, Wisconsin and General Atomics DIII-D National Fusion Facility, San Diego, California
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Affiliation(s)
| | - D. A. Humphreys
- General Atomics DIII-D National Fusion Facility, San Diego, California
| | - A. G. Kellman
- General Atomics DIII-D National Fusion Facility, San Diego, California
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Whyte DG, Minervini J, LaBombard B, Marmar E, Bromberg L, Greenwald M. Smaller & Sooner: Exploiting High Magnetic Fields from New Superconductors for a More Attractive Fusion Energy Development Path. J Fusion Energ 2016. [DOI: 10.1007/s10894-015-0050-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Wright GM, Barnard HA, Kesler LA, Peterson EE, Stahle PW, Sullivan RM, Whyte DG, Woller KB. An experiment on the dynamics of ion implantation and sputtering of surfaces. Rev Sci Instrum 2014; 85:023503. [PMID: 24593357 DOI: 10.1063/1.4861917] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A major impediment towards a better understanding of the complex plasma-surface interaction is the limited diagnostic access to the material surface while it is undergoing plasma exposure. The Dynamics of ION Implantation and Sputtering Of Surfaces (DIONISOS) experiment overcomes this limitation by uniquely combining powerful, non-perturbing ion beam analysis techniques with a steady-state helicon plasma exposure chamber, allowing for real-time, depth-resolved in situ measurements of material compositions during plasma exposure. Design solutions are described that provide compatibility between the ion beam analysis requirements in the presence of a high-intensity helicon plasma. The three primary ion beam analysis techniques, Rutherford backscattering spectroscopy, elastic recoil detection, and nuclear reaction analysis, are successfully implemented on targets during plasma exposure in DIONISOS. These techniques measure parameters of interest for plasma-material interactions such as erosion/deposition rates of materials and the concentration of plasma fuel species in the material surface.
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Affiliation(s)
- G M Wright
- Plasma Science and Fusion Center, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - H A Barnard
- Plasma Science and Fusion Center, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - L A Kesler
- Plasma Science and Fusion Center, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - E E Peterson
- Plasma Science and Fusion Center, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - P W Stahle
- Plasma Science and Fusion Center, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - R M Sullivan
- Plasma Science and Fusion Center, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - D G Whyte
- Plasma Science and Fusion Center, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - K B Woller
- Plasma Science and Fusion Center, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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Rice JE, Hughes JW, Diamond PH, Kosuga Y, Podpaly YA, Reinke ML, Greenwald MJ, Gürcan ÖD, Hahm TS, Hubbard AE, Marmar ES, McDevitt CJ, Whyte DG. Edge temperature gradient as intrinsic rotation drive in Alcator C-Mod tokamak plasmas. Phys Rev Lett 2011; 106:215001. [PMID: 21699305 DOI: 10.1103/physrevlett.106.215001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Indexed: 05/31/2023]
Abstract
Intrinsic rotation has been observed in I-mode plasmas from the C-Mod tokamak, and is found to be similar to that in H mode, both in its edge origin and in the scaling with global pressure. Since both plasmas have similar edge ∇T, but completely different edge ∇n, it may be concluded that the drive of the intrinsic rotation is the edge ∇T rather than ∇P. Evidence suggests that the connection between gradients and rotation is the residual stress, and a scaling for the rotation from conversion of free energy to macroscopic flow is calculated.
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Affiliation(s)
- J E Rice
- PSFC, MIT, Cambridge, Massachusetts 02139, USA
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Hartwig ZS, Whyte DG. Simulated plasma facing component measurements for an in situ surface diagnostic on Alcator C-Mod. Rev Sci Instrum 2010; 81:10E106. [PMID: 21033971 DOI: 10.1063/1.3478634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The ideal in situ plasma facing component (PFC) diagnostic for magnetic fusion devices would perform surface element and isotope composition measurements on a shot-to-shot (∼10 min) time scale with ∼1 μm depth and ∼1 cm spatial resolution over large areas of PFCs. To this end, the experimental adaptation of the customary laboratory surface diagnostic--nuclear scattering of MeV ions--to the Alcator C-Mod tokamak is being guided by ACRONYM, a Geant4 synthetic diagnostic. The diagnostic technique and ACRONYM are described, and synthetic measurements of film thickness for boron-coated PFCs are presented.
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Affiliation(s)
- Z S Hartwig
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, 77 Massachusetts Ave., NW17-155, Cambridge, Massachusetts 02139, USA.
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Ochoukov R, Whyte DG, Lipschultz B, Labombard B, Wukitch S. Interpretation and implementation of an ion sensitive probe as a plasma potential diagnostic. Rev Sci Instrum 2010; 81:10E111. [PMID: 21033976 DOI: 10.1063/1.3483192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
An ion sensitive probe (ISP) is developed as a robust diagnostic for measuring plasma potentials (Φ(P)) in magnetized plasmas. The ISP relies on the large difference between the ion and electron gyroradii (ρ(i)/ρ(e)∼60) to reduce the electron collection at a collector recessed behind a separately biased wall distance ∼ρ(i). We develop a new ISP method to measure the plasma potential that is independent of the precise position and shape of the collector. Φ(P) is found as the wall potential when charged current to the probe collector vanishes during the voltage sweep. The plasma potentials obtained from the ISP match Φ(P) measured with an emissive probe over a wide range of plasma conditions in a small magnetized plasma.
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Affiliation(s)
- R Ochoukov
- PSFC, MIT, 77 Mass. Avenue, Cambridge, Massachusetts 02139, USA.
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McLean AG, Davis JW, Stangeby PC, Brooks NH, Ellis RM, Haasz AA, Rudakov DL, West WP, Whyte DG, Wong CPC. Porous plug gas injection systems for studies of hydrocarbon dissociation and transport in the DIII-D tokamak. Rev Sci Instrum 2009; 80:043501. [PMID: 19405654 DOI: 10.1063/1.3100180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A probe has been designed, constructed, and successfully used to inject methane into the DIII-D lower divertor in a manner imitating natural release by chemical erosion. This porous plug injector (PPI) probe consists of a self-contained gas reservoir with an integrated pressure gauge and a 3 cm diameter porous surface through which gas is injected into the lower divertor of the tokamak. The probe is positioned flush with the divertor target surface by means of the divertor materials evaluation system. Two gas delivery systems were developed: in the first, gas flow is regulated by a remotely controlled microvalve and in the second by a fixed micro-orifice flow restrictor. Because of the large area of the porous surface through which gas is admitted, the injected hydrocarbon molecules see a local carbon surface (>90% carbon) similar to that seen by hydrocarbons being emitted by chemical sputtering from surrounding carbon tiles. The distributed gas source also reduces the disturbance to the local plasma while providing sufficient signal for spectroscopic detection. In situ spectroscopic measurements with the PPI in DIII-D allow the direct calibration of response for measured plasma conditions from a known influx of gas.
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Affiliation(s)
- A G McLean
- Institute for Aerospace Studies, University of Toronto, 4925 Dufferin St., Toronto, Ontario M3H 5T6, Canada.
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Whyte DG, Jernigan TC, Humphreys DA, Hyatt AW, Lasnier CJ, Parks PB, Evans TE, Rosenbluth MN, Taylor PL, Kellman AG, Gray DS, Hollmann EM, Combs SK. Mitigation of tokamak disruptions using high-pressure gas injection. Phys Rev Lett 2002; 89:055001. [PMID: 12144446 DOI: 10.1103/physrevlett.89.055001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2002] [Indexed: 05/23/2023]
Abstract
High-pressure gas-jet injection of neon and argon is shown to be a simple and robust method to mitigate the deleterious effects of disruptions on the DIII-D tokamak. The gas jet penetrates to the central plasma at its sonic velocity. The deposited species dissipates >95% of the plasma by radiation and substantially reduces mechanical stresses on the vessel caused by poloidal halo currents. The gas-jet species-charge distribution can include >50% fraction neutral species which inhibits runaway electrons. The favorable scaling of this technique to burning fusion plasmas is discussed.
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Affiliation(s)
- D G Whyte
- University of California, San Diego, California, USA
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11
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Forest CB, Petty CC, Austin ME, Baity FW, Burrell KH, Chiu SC, Chu MS, deGrassie JS, Gohil P, Hyatt AW, Ikezi H, Lazarus EA, Murakami M, Pinsker RI, Porkolab M, Prater R, Rice BW, Staebler GM, Strait EJ, Taylor TS, Whyte DG. Energy Transport in Tokamak Plasmas with Central Current Density Control Using Fast Waves. Phys Rev Lett 1996; 77:3141-3144. [PMID: 10062144 DOI: 10.1103/physrevlett.77.3141] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Forest CB, Kupfer K, Luce TC, Politzer PA, Lao LL, Wade MR, Whyte DG, Wròblewski D. Determination of the noninductive current profile in tokamak plasmas. Phys Rev Lett 1994; 73:2444-2447. [PMID: 10057061 DOI: 10.1103/physrevlett.73.2444] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Watt PC, Spence RA, Campbell RC, McGurk JJ, Whyte DG. A policy of combined barium meal and cholecystogram for dyspeptic patients. Lancet 1983; 2:1249. [PMID: 6139590 DOI: 10.1016/s0140-6736(83)91293-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Abstract
A case of acute thoracic inlet obstruction presenting as a rare complication of achalasia is described. The probable mechanism, diagnosis, and management are discussed.
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Abstract
A new method of acute urography suitable for use in any general hospital is described. It takes only 30 minutes and can be performed by the duty radiographer.The method has proved invaluable in the diagnosis and differentiation of renal colic. With radiation safeguards, it may be of value in pregnancy. It has been found useful in renal trauma and in the differential diagnosis of haematuria.
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