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Articles With Citations to Z. Abou-Assaleh

Theoretical Plasma Physics

Controlled Thermonuclear Fusion Energy

2006

Thin Solid Films

Volumes 506–507, 26 May 2006, Pages 665-668

https://escholarship.org/content/

qt5k75n1jv/qt5k75n1jv.pdf

Laser-induced fluorescence measurements for plasma processing

R.McWilliams, H.Boehmer, D.Edrich, L.Zhao, D.Zimmerman

Department of Physics and Astronomy, University of California, Irvine, CA, USA

Available online 12 September 2005.

https://doi.org/10.1016/j.tsf.2005.08.113

Abstract

Laser-induced fluorescence (LIF) has been used in plasmas for over 20 years and in plasma processing for about 10 years. Complexity and expense of this non-invasive diagnostic have limited it to laboratories although diode lasers offer hope for real-time processing metrology. LIF offers time- and space-resolved ion distribution functions, allowing study of plasma thermodynamics and transport and calibration of energy analyzers and mass flow probes. LIF was applied to an RF ion beam source (Veeco/Ion Tech). Ion distributions are compared with energy analyzer results and manufacturer's estimates. LIF distributions show narrower beam velocity spread, and better resolution, than energy analyzers. Beam ion energy can be measured rather than relying on manufacturer's estimate. Spatial resolution of LIF has permitted measurement of multidimensional ion velocity distributions in the bulk, and entering the sheath, near a conducting boundary wall.

Keywords

Plasma processing and deposition Fluorescence

References

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[26] S.L. Gulick, et al. (Z. Abou-Assaleh) ..., J. Nucl. Mater. 176 & 177 (1990) 1059.

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Thin Solid Films
Volumes 506-507, 26 May 2006, Pages 674-678
The Joint Meeting of 7th APCPST(Asia Pacific Conference on Plasma Science and Technology) and 17th SPSM (Symposium on Plasma Science for Materials) - 7th APCPST/17th SPSM

Ion flow and sheath physics studies in multiple ion species plasmas using diode laser based laser-induced fluorescence

G.D. Severn^{1, a,} , Xu Wang^b, Eunsuk Ko^b, N. Hershkowitz^b, M.M. Turner^c and R. McWilliams^d
aDepartment of Physics, University of San Diego, San Diego, CA 92110, USA
^bEngineering Physics Department, University of Wisconsin-Madison, Madison, WI 53706, USA
^cNational Center for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9, Ireland
^dDepartment of Physics and Astronomy, University of California, Irvine, CA 92049, USA

Abstract

Diode lasers have proved to be a valuable light source for laser-induced fluorescence (LIF) measurements for plasma science since the early 1990s, and they have recently improved the state of the art of measuring ion flow from ion velocity distribution functions (ivdfs) at the sheath–presheath boundary in single and multiple ion species plasmas. In the case of a low temperature two ion species plasma (ArI + HeI), we were the first to show experimentally that ion species may reach the sheath edge flowing at a very different speed than that expected from the single species Bohm Criterion (ArII ions exceed the individual Bohm flow speed by almost a factor of 2 at the sheath edge). Simulation results are found to agree. Diode laser technology relevant to LIF measurements in multiple ion species plasmas is discussed with the aim of addressing outstanding problems in sheath formation in such plasmas.

Keywords

Plasma sheath; Plasma diagnostics; Plasma spectroscopy

 

Contrib. Plasma Phys. 46, No. 1-2, 3 – 191 (2006) /

DOI 10.1002/ctpp.200610001

Plasma Edge Physics with B2-Eirene

R. Schneider1, X. Bonnin2, K. Borrass3, D. P. Coster3, H. Kastelewicz4, D. Reiter5, V. A. Rozhansky6, and B. J. Braams7

1 Max-Planck-Institut f¨ur Plasmaphysik, EURATOMAssociation, Teilinstitut Greifswald,Wendelsteinstr.1, D-17491 Greifswald, Germany

2 LIMHP, CNRS-UPR 1311, Universit´e Paris XIII, 99, avenue JB Cl´ement, F-93430 Villetaneuse, France

3 Max-Planck-Institut f¨ur Plasmaphysik, EURATOMAssociation, Boltzmannstraße 2, D-85748 Garching, Germany

4 Max-Planck-Institut f¨ur Plasmaphysik, EURATOMAssociation, Mohrenstraße 41, D-10117 Berlin, Germany

5 Institut f¨ur Plasmaphysik, Forschungszentrum J¨ulich, Trilateral Euregio Cluster, D-52425 J¨ulich, Germany

6 Saint-Petersburg State Polytechnical University, Polytechnicheskaya 29, 195251 St. Petersburg, Russia

7 Emory University, Mathematics and Science Center, 400 Dowman Drive, Atlanta, Georgia 30322, USA

Received 8 March 2005, accepted 18 September 2005

Published online 25 Januar 2006

Key words Plasma edge, plasma modelling, plasma codes, plasma transport boundary layer.

PACS 52.27.Lw, 52.65.Rr, 52.50.Qt

Abstract

The B2-Eirene code package was developed to give better insight into the physics in the scrape-off layer (SOL), which is defined as the region of open field-lines intersecting walls. The SOL is characterised by the competition of parallel and perpendicular transport defining by this a 2D system. The description of the plasma-wall interaction due to the existence of walls and atomic processes are necessary ingredients for an understanding of the scrape-off layer. This paper concentrates on understanding the basic physics by combining the results of the code with experiments and analytical models or estimates. This work will mainly focus on divertor tokamaks, but most of the arguments and principles can be easily adapted also to other concepts like island divertors in stellarators or limiter devices.

The paper presents the basic equations for the plasma transport and the basic models for the neutral transport. This defines the basic ingredients for the SOLPS (Scrape-Off Layer Plasma Simulator) code package. A first level of understanding is approached for pure hydrogenic plasmas based both on simple models and simulations with B2-Eirene neglecting drifts and currents. The influence of neutral transport on the different operation regimes is here the main topic. This will finish with time-dependent phenomena for the pure plasma, so-called Edge Localised Modes (ELMs). Then, the influence of impurities on the SOL plasma is discussed. For the understanding of impurity physics in the SOL one needs a rather complex combination of different aspects. The impurity production process has to be understood, then the effects of impurities in terms of radiation losses have to be included and finally impurity transport is necessary. This will be introduced with rising complexity starting with simple estimates, analysing then the detailed parallel force balance and the flow pattern of impurities. Using this, impurity compression and radiation instabilities will be studied. This part ends, combining all the elements introduced before, with specific, detailed results from different machines. Then, the effect of drifts and currents is introduced and their consequences presented. Finally, some work on deriving scaling laws for the anomalous turbulent transport based on automatic edge transport code fitting procedures will be described.

Japanese Journal of Applied Physics
Vol. 45, No. 7, 2006, pp. 5945-5950
URL : http://jjap.ipap.jp/link?JJAP/45/5945/
DOI : 10.1143/JJAP.45.5945

Determination of Plasma Flow Velocity by Mach Probe and Triple Probe with Correction by Laser-Induced Fluorescence in Unmagnetized Plasmas

Yong-Sup Choi^*, Hyun-Jong Woo, Kyu-Sun Chung^**, Myoung-Jae Lee, David Zimmerman¹ and Roger McWilliams¹

Electric Probe Applications Laboratory (ePAL), Hanyang University, Seoul 133-791, Korea
¹Department of Physics and Astronomy, University of California, Irvine, CA 92697, U.S.A.

(Received March 16, 2005; revised September 19, 2005; accepted February 23, 2006; published online July 7, 2006)

Abstract

Plasma flow velocity was measured by Mach probe (MP) and laser-induced fluorescence (LIF) methods in unmagnetized plasmas with supersonic ion beams. Since the ion gyro-radius was much larger than the probe radius, unmagnetized Mach probe theory was used to determine plasma flow in argon RF plasma with a weak magnetic field (<200 G). In order to determine flow velocities, the Mach probe is calibrated via LIF in the absence of the ion beam, where existing probe theories may be valid although they use different geometries (sphere and plane) and analyzing tools [particle-in-cell (PIC) and kinetic models]. For the comparison of the average plasma flow velocities by MP and LIF, the supersonic ion beam velocity was measured by LIF and then incorporated into a simple formula for average plasma velocity with provisions for background plasma density and beam-corrected electron temperature (T_e) measured by a triple probe.

Keywords

plasma flow velocity, Mach probe, triple probe, laser induced fluorescence, LIF, unmagnetized plasma

^*Present address: Production Engineering Center, Samsung SDI Co., Ltd., Suwon, Gyeonggi 575, Korea.
^**Corresponding author: E-mail address: kschung@hanyang.ac.kr

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References

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10. S. L. Gulick, B. L. Stansfield, Z. Abou-Assaleh, C. Boucher, J. P. Matte, T. W. Johnston and R. Marchand: J. Nucl. Mater. 176–177 (1990) 1064.

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