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Grenfell G, Manz P, Conway G, Eich T, Adamek J, Brida D, Komm M, Nishizawa T, Griener M, Tal B, Stroth U. Turbulence in the near scrape-off layer towards the L-mode density limit in ASDEX-Upgrade. Nuclear Materials and Energy 2022. [DOI: 10.1016/j.nme.2022.101277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Grenfell G, Adamek J, Komm M, Brida D, Conway GD, Manz P, Tolias P, Eich T, Sestak D, Herrmann A, Nishizawa T, Stroth U. High-heat flux ball-pen probe head in ASDEX-Upgrade. Rev Sci Instrum 2022; 93:023507. [PMID: 35232131 DOI: 10.1063/5.0075846] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
A new high heat flux ball-pen probe head installed on the midplane manipulator is currently being used in ASDEX-Upgrade (AUG). The probe was designed to withstand high heat fluxes making possible the investigation of the plasma edge under harsh conditions, such as low power H-mode. Composed of seven pins (four Langmuir probes, mounted in two Mach probe pairs, and three ball-pen probes), the new probe head allows us to measure several plasma parameters simultaneously and with high temporal resolution. A novel method to correct the sheath potential dynamically accounting for the total secondary electron emission is introduced together with applications to obtain the electron temperature and plasma potential profiles. The total secondary electron emission yield is obtained from particle in cell simulations in AUG condition and probe realistic impact angle with respect to the magnetic field. Finally, the probe capability to investigate turbulence around the separatrix of AUG is discussed.
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Affiliation(s)
- G Grenfell
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, Garching, Germany
| | - J Adamek
- Institute of Plasma Physics of the CAS, Za Slovankou 3, 182 00 Prague 8, Czech Republic
| | - M Komm
- Institute of Plasma Physics of the CAS, Za Slovankou 3, 182 00 Prague 8, Czech Republic
| | - D Brida
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, Garching, Germany
| | - G D Conway
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, Garching, Germany
| | - P Manz
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, Garching, Germany
| | - P Tolias
- Division of Space and Plasma Physics, Association EUROfusion-VR, Royal Institute of Technology KTH, Teknikringen 31, 100 44 Stockholm, Sweden
| | - T Eich
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, Garching, Germany
| | - D Sestak
- Institute of Plasma Physics of the CAS, Za Slovankou 3, 182 00 Prague 8, Czech Republic
| | - A Herrmann
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, Garching, Germany
| | - T Nishizawa
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, Garching, Germany
| | - U Stroth
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, Garching, Germany
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3
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Affiliation(s)
- Oost Van Guido
- Department of Applied Physics Ghent University J.Plateaustraat 22 B-9000 Gent, Belgium
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Grover O, Adamek J, Seidl J, Devitre A, Sos M, Vondracek P, Bilkova P, Hron M. First simultaneous measurements of Reynolds stress with ball-pen and Langmuir probes. Rev Sci Instrum 2017; 88:063501. [PMID: 28668002 DOI: 10.1063/1.4984240] [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: 06/07/2023]
Abstract
A new multi-pin probe head was installed and tested at the COMPASS tokamak. The probe head consists of several ball-pen and Langmuir probes in similar geometric configurations, which enables fast, simultaneous measurements of the radial and poloidal electric field components from differences of plasma or floating potentials using appropriately positioned ball-pen or Langmuir probes, respectively. The fast measurements of the radial electric field are compared with other methods of measuring selected frequency components of the radial electric field. The radial profiles of the Reynolds stress calculated from correlations of electric field fluctuations obtained by either probe type are compared along with their spectral composition. Lower Reynolds stress values are found for Langmuir probes in comparison to ball-pen probes due to negative contributions from higher frequency fluctuations possibly associated with electron temperature fluctuations.
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Affiliation(s)
- Ondrej Grover
- Faculty of Nuclear Physics, Czech Technical University in Prague, Prague 115 19, Czech Republic
| | - Jiri Adamek
- Institute of Plasma Physics, The Czech Academy of Sciences, Prague 182 00, Czech Republic
| | - Jakub Seidl
- Institute of Plasma Physics, The Czech Academy of Sciences, Prague 182 00, Czech Republic
| | - Alexis Devitre
- Institute of Plasma Physics, The Czech Academy of Sciences, Prague 182 00, Czech Republic
| | - Miroslav Sos
- Institute of Plasma Physics, The Czech Academy of Sciences, Prague 182 00, Czech Republic
| | - Petr Vondracek
- Institute of Plasma Physics, The Czech Academy of Sciences, Prague 182 00, Czech Republic
| | - Petra Bilkova
- Institute of Plasma Physics, The Czech Academy of Sciences, Prague 182 00, Czech Republic
| | - Martin Hron
- Institute of Plasma Physics, The Czech Academy of Sciences, Prague 182 00, Czech Republic
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Tan M, Stone DR, Triana JC, Almagri AF, Fiksel G, Ding W, Sarff JS, McCollam KJ, Li H, Liu W. A multi-channel capacitive probe for electrostatic fluctuation measurement in the Madison Symmetric Torus reversed field pinch. Rev Sci Instrum 2017; 88:023502. [PMID: 28249474 DOI: 10.1063/1.4975095] [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: 06/06/2023]
Abstract
A 40-channel capacitive probe has been developed to measure the electrostatic fluctuations associated with the tearing modes deep into Madison Symmetric Torus (MST) reversed field pinch plasma. The capacitive probe measures the ac component of the plasma potential via the voltage induced on stainless steel electrodes capacitively coupled with the plasma through a thin annular layer of boron nitride (BN) dielectric (also serves as the particle shield). When bombarded by the plasma electrons, BN provides a sufficiently large secondary electron emission for the induced voltage to be very close to the plasma potential. The probe consists of four stalks each with ten cylindrical capacitors that are radially separated by 1.5 cm. The four stalks are arranged on a 1.3 cm square grid so that at each radial position, there are four electrodes forming a square grid. Every two adjacent radial sets of four electrodes form a cube. The fluctuating electric field can be calculated by the gradient of the plasma potential fluctuations at the eight corners of the cube. The probe can be inserted up to 15 cm (r/a = 0.7) into the plasma. The capacitive probe has a frequency bandwidth from 13 Hz to 100 kHz, amplifier-circuit limit, sufficient for studying the tearing modes (5-30 kHz) in the MST reversed-field pinch.
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Affiliation(s)
- Mingsheng Tan
- CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Douglas R Stone
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Joseph C Triana
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | | - Gennady Fiksel
- Center for Ultrafast Optical Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Weixing Ding
- CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - John S Sarff
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Karsten J McCollam
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Hong Li
- CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Wandong Liu
- CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
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Adamek J, Müller HW, Silva C, Schrittwieser R, Ionita C, Mehlmann F, Costea S, Horacek J, Kurzan B, Bilkova P, Böhm P, Aftanas M, Vondracek P, Stöckel J, Panek R, Fernandes H, Figueiredo H. Profile measurements of the electron temperature on the ASDEX Upgrade, COMPASS, and ISTTOK tokamak using Thomson scattering, triple, and ball-pen probes. Rev Sci Instrum 2016; 87:043510. [PMID: 27131677 DOI: 10.1063/1.4945797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The ball-pen probe (BPP) technique is used successfully to make profile measurements of the electron temperature on the ASDEX Upgrade (Axially Symmetric Divertor Experiment), COMPASS (COMPact ASSembly), and ISTTOK (Instituto Superior Tecnico TOKamak) tokamak. The electron temperature is provided by a combination of the BPP potential (ΦBPP) and the floating potential (Vfl) of the Langmuir probe (LP), which is compared with the Thomson scattering diagnostic on ASDEX Upgrade and COMPASS. Excellent agreement between the two diagnostics is obtained for circular and diverted plasmas and different heating mechanisms (Ohmic, NBI, ECRH) in deuterium discharges with the same formula Te = (ΦBPP - Vfl)/2.2. The comparative measurements of the electron temperature using BPP/LP and triple probe (TP) techniques on the ISTTOK tokamak show good agreement of averaged values only inside the separatrix. It was also found that the TP provides the electron temperature with significantly higher standard deviation than BPP/LP. However, the resulting values of both techniques are well in the phase with the maximum of cross-correlation function being 0.8.
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Affiliation(s)
- J Adamek
- Institute of Plasma Physics, Prague, Czech Republic
| | - H W Müller
- Max-Planck-Institute for Plasma Physics, Garching near Munich, Germany
| | - C Silva
- Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - R Schrittwieser
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria
| | - C Ionita
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria
| | - F Mehlmann
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria
| | - S Costea
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria
| | - J Horacek
- Institute of Plasma Physics, Prague, Czech Republic
| | - B Kurzan
- Max-Planck-Institute for Plasma Physics, Garching near Munich, Germany
| | - P Bilkova
- Institute of Plasma Physics, Prague, Czech Republic
| | - P Böhm
- Institute of Plasma Physics, Prague, Czech Republic
| | - M Aftanas
- Institute of Plasma Physics, Prague, Czech Republic
| | - P Vondracek
- Institute of Plasma Physics, Prague, Czech Republic
| | - J Stöckel
- Institute of Plasma Physics, Prague, Czech Republic
| | - R Panek
- Institute of Plasma Physics, Prague, Czech Republic
| | - H Fernandes
- Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - H Figueiredo
- Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
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Agah KM, Salar Elahi A, Ghoranneviss M. Review on Plasma Edge Analysis Using the Auto-Correlation and Probability Distributions of Fluctuations. J Fusion Energ 2015. [DOI: 10.1007/s10894-015-9969-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Walkden NR, Adamek J, Allan S, Dudson BD, Elmore S, Fishpool G, Harrison J, Kirk A, Komm M. Profile measurements in the plasma edge of mega amp spherical tokamak using a ball pen probe. Rev Sci Instrum 2015; 86:023510. [PMID: 25725845 DOI: 10.1063/1.4908572] [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: 06/04/2023]
Abstract
The ball pen probe (BPP) technique is used successfully to make profile measurements of plasma potential, electron temperature, and radial electric field on the Mega Amp Spherical Tokamak. The potential profile measured by the BPP is shown to significantly differ from the floating potential both in polarity and profile shape. By combining the BPP potential and the floating potential, the electron temperature can be measured, which is compared with the Thomson scattering (TS) diagnostic. Excellent agreement between the two diagnostics is obtained when secondary electron emission is accounted for in the floating potential. From the BPP profile, an estimate of the radial electric field is extracted which is shown to be of the order ∼1 kV/m and increases with plasma current. Corrections to the BPP measurement, constrained by the TS comparison, introduce uncertainty into the ER measurements. The uncertainty is most significant in the electric field well inside the separatrix. The electric field is used to estimate toroidal and poloidal rotation velocities from E × B motion. This paper further demonstrates the ability of the ball pen probe to make valuable and important measurements in the boundary plasma of a tokamak.
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Affiliation(s)
- N R Walkden
- CCFE, Culham Science Centre, Abingdon,Oxon OX14 3DB, United Kingdom
| | - J Adamek
- Institute of Plasma Physics of AS CR, v. v. i., Za Slovankou 3, 182 00 Praha 8, Czech Republic
| | - S Allan
- CCFE, Culham Science Centre, Abingdon,Oxon OX14 3DB, United Kingdom
| | - B D Dudson
- Department of Physics, York Plasma Institute, University of York, Heslington, York YO10 5DD, United Kingdom
| | - S Elmore
- CCFE, Culham Science Centre, Abingdon,Oxon OX14 3DB, United Kingdom
| | - G Fishpool
- CCFE, Culham Science Centre, Abingdon,Oxon OX14 3DB, United Kingdom
| | - J Harrison
- CCFE, Culham Science Centre, Abingdon,Oxon OX14 3DB, United Kingdom
| | - A Kirk
- CCFE, Culham Science Centre, Abingdon,Oxon OX14 3DB, United Kingdom
| | - M Komm
- Institute of Plasma Physics of AS CR, v. v. i., Za Slovankou 3, 182 00 Praha 8, Czech Republic
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Meshkani S, Ghoranneviss M, Salar Elahi A, Lafouti M. Design and Fabrication of Comparative Langmuir Ball-Pen Probe (LBP) for the Tokamak. J Fusion Energ 2015; 34:394-7. [DOI: 10.1007/s10894-014-9811-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Brunner D, LaBombard B, Ochoukov R, Whyte D. Scanning ion sensitive probe for plasma profile measurements in the boundary of the Alcator C-Mod tokamak. Rev Sci Instrum 2013; 84:053507. [PMID: 23742551 DOI: 10.1063/1.4807699] [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: 06/02/2023]
Abstract
A new Ion Sensitive Probe head has been created for the outer-midplane scanning probe system on the Alcator C-Mod tokamak. The new probe head contains three elements: an ion sensitive probe to measure ion temperature and plasma potential, a Langmuir probe to measure electron temperature, density, and floating potential, and a second Langmuir probe to measure ion saturation current and the density fluctuations arising from ''blob'' events. The ion sensitive probe current is normalized to this measurement to reduced deleterious effects of the strong fluctuations. Design of the high heat flux probe (>100 MW/m(2)) and initial results are presented.
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Affiliation(s)
- D Brunner
- PSFC, MIT, Cambridge, Massachusetts 02139, USA
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Hsieh TY, Kawamori E, Nishida Y. Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma. Rev Sci Instrum 2013; 84:023502. [PMID: 23464206 DOI: 10.1063/1.4790175] [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: 06/01/2023]
Abstract
This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas.
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Affiliation(s)
- Tung-Yuan Hsieh
- Institute of Space, Astrophysical and Plasma Sciences, National Cheng Kung University, Taiwan.
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Bousselin G, Cavalier J, Pautex JF, Heuraux S, Lemoine N, Bonhomme G. Design and validation of the ball-pen probe for measurements in a low-temperature magnetized plasma. Rev Sci Instrum 2013; 84:013505. [PMID: 23387648 DOI: 10.1063/1.4775491] [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: 06/01/2023]
Abstract
Ball-pen probes have been used in fusion devices for direct measurements of the plasma potential. Their application in low-temperature magnetized plasma devices is still subject to studies. In this context, a ball-pen probe has been recently implemented on the linear plasma device Mirabelle. Produced by a thermionic discharge, the plasma is characterized by a low electron temperature and a low density. Plasma confinement is provided by an axial magnetic field that goes up to 100 mT. The principle of the ball-pen probe is to adjust the saturation current ratio to 1 by reducing the electron current contribution. In that case, the floating potential of the probe is close to the plasma potential. A thorough study of the ball-pen probe operation is performed for different designs of the probe over a large set of plasma conditions. Comparisons between ball-pen, Langmuir, and emissive probes are conducted in the same plasma conditions. The ball-pen probe is successfully measuring the plasma potential in these specific plasma conditions only if an adapted electronics and an adapted probe size to the plasma characteristic lengths (λ(D), ρ(ce)) are used.
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Affiliation(s)
- G Bousselin
- IJL, Université de Lorraine, CNRS (UMR 7198), BP 70239, 54506 Vandoeuvre-lès-Nancy, France.
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Affiliation(s)
- Guido Van Oost
- Department of Applied Physics Ghent University J. Plateaustraat 22 B-9000 Gent, Belgium
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Affiliation(s)
- Guido Van Oost
- Department of Applied Physics Ghent University J. Plateaustraat 22 B-9000 Gent, Belgium
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Affiliation(s)
- Guido Van Oost
- Department of Applied Physics Ghent University Rozier 44 B-9000 Gent, Belgium
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