Updated on 2024/10/04

Information

 

写真a

 
NISHIZAWA TAKASHI
 
Organization
Research Institute for Applied Mechanics Division of Nuclear Fusion Dynamics Assistant Professor
Interdisciplinary Graduate School of Engineering Sciences Department of Interdisciplinary Engineering Sciences（Joint Appointment）
Title
Assistant Professor
Contact information
メールアドレス
External link

Degree

  • University of Wisconsin, Madison

Research Interests・Research Keywords

  • Research theme：plasma turbulence

    Keyword：turbulence

    Research period： 2022.1 - 2022.6

Awards

  • 若手奨励賞

    2020.3   日本物理学会   逆磁場ピンチプラズマにおけるドリフト波乱流に関する研究

  • 日本物理学会領域２若手奨励賞

    2019.9   日本物理学会   逆磁場ピンチプラズマにおけるドリフト波乱流に関する研究

  • 領域２学生優秀発表賞

    2017.11   日本物理学会   Measurements of Impurity Transport Associated with Drift-wave Turbulence in a Reversed Field Pinch

Papers

  • Overview of Large Helical Device experiments of basic plasma physics for solving crucial issues in reaching burning plasma conditions

    Ida K., Yoshinuma M., Kobayashi M., Kobayashi T., Kenmochi N., Nespoli F., Magee R.M., Warmer F., Dinklage A., Matsuyama A., Sakamoto R., Nasu T., Tokuzawa T., Kinoshita T., Tanaka K., Tamura N., Nagaoka K., Nishiura M., Takemura Y., Ogawa K., Motojima G., Oishi T., Morishita Y., Varela J., Hayashi W.H.J., Markl M., Bouvain H., Liang Y., Leconte M., Moseev D., Moiseenko V.E., Albert C.G., Allfrey I., Alonso A., Arellano F.J., Ashikawa N., Azegami A., Bardoczi L., van Berkel M., Beurskens M., Binderbaue M.W., Bortolon A., Brezinsek S., Bussiahn R., Cappa A., Carralero D., Chan I.C., Cheng J., Dai X., Den Hartog D.J., Dhard C.P., Ding F., Ejiri A., Ertmer S., Fornal T., Fujita K., Fujiwara Y., Funaba H., Garcia L., Garcia-Regana J.M., Garcia-Cortés I., Garkusha I.E., Gates D.A., Ghai Y., Gilson E.P., Gota H., Goto M., Green E.M., Haak V., Hamaguchi S., Hanada K., Hara H., Hartmann D., Hayashi Y., Henning T., Hidalgo C., Hillairet J., Hutton R., Ido T., Igami H., Ikeda K., Inagaki S., Ishizawa A., Ito S., Isobe M., Isobe Y., Ivkovic M., Jiang Z., Jo J., Kamio S., Kasahara H., Kato D., Katoh Y., Kawachi Y., Kawamoto Y., Kawamura G., Kawate T., Kazakov Y.O., Klumper V., Knieps A.

    Nuclear Fusion   64 ( 11 )   2024.11   （ ISSN:00295515 ）

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    Publisher：Nuclear Fusion  

    Recently, experiments on basic plasma physics issues for solving future problems in fusion energy have been performed on a Large Helical Device. There are several problems to be solved in future devices for fusion energy. Emerging issues in burning plasma are: alpha-channeling (ion heating by alpha particles), turbulence and transport in electron dominant heating helium ash exhaust, reduction of the divertor heat load. To solve these problems, understanding the basic plasma physics of (1) wave-particle interaction through (inverse) Landau damping, (2) characteristics of electron-scale (high-k) turbulence, (3) ion mixing and the isotope effect, and (4) turbulence spreading and detachment, is necessary. This overview discusses the experimental studies on these issues and turbulent transport in multi-ion plasma and other issues in the appendix.

    DOI： 10.1088/1741-4326/ad3a7a

    Scopus

  • Overview of ASDEX upgrade results in view of ITER and DEMO

    Zohm H., Alessi E., Angioni C., Arden N., Artigues V., Astrain M., Asunta O., Balden M., Bandaru V., Banon Navarro A., Bauer M., Bergmann A., Bergmann M., Bernardo J., Bernert M., Biancalani A., Bielajew R., Bilato R., Birkenmeier G., Blanken T., Bobkov V., Bock A., Bock L., Body T., Bolzonella T., Bonanomi N., Bortolon A., Böswirth B., Bottereau C., Bottino A., van den Brand H., Brenzke M., Brezinsek S., Brida D., Brochard F., Buchanan J., Buhler A., Burckhart A., Camenen Y., Cannas B., Cano Megías P., Carlton D., Carr M., Carvalho P., Castaldo C., Castillo Castillo A., Cathey A., Cavedon M., Cazzaniga C., Challis C., Chankin A., Chomiczewska A., Cianfarani C., Clairet F., Coda S., Coelho R., Coenen J., Colas L., Conway G., Costea S., Coster D., Cote T., Creely A., Croci G., Cruz Zabala D., Cseh G., Cziegler I., D’Arcangelo O., Dal Molin A., David P., Day C., de Baar M., de Marné P., Delogu R., Denner P., Di Siena A., Dibon M., Dominguez-Palacios Durán J., Dunai D., Dreval M., Dunne M., Duval B., Dux R., Eich T., Elgeti S., Encheva A., Esposito B., Fable E., Faitsch M., Fajardo Jimenez D., Fantz U., Farnik M., Faugel H., Felici F., Ficker O., Figueredo A., Fischer R., Ford O., Frassinetti L., Fröschle M.

    Nuclear Fusion   64 ( 11 )   2024.11   （ ISSN:00295515 ）

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    Publisher：Nuclear Fusion  

    Experiments on ASDEX Upgrade (AUG) in 2021 and 2022 have addressed a number of critical issues for ITER and EU DEMO. A major objective of the AUG programme is to shed light on the underlying physics of confinement, stability, and plasma exhaust in order to allow reliable extrapolation of results obtained on present day machines to these reactor-grade devices. Concerning pedestal physics, the mitigation of edge localised modes (ELMs) using resonant magnetic perturbations (RMPs) was found to be consistent with a reduction of the linear peeling-ballooning stability threshold due to the helical deformation of the plasma. Conversely, ELM suppression by RMPs is ascribed to an increased pedestal transport that keeps the plasma away from this boundary. Candidates for this increased transport are locally enhanced turbulence and a locked magnetic island in the pedestal. The enhanced D-alpha (EDA) and quasi-continuous exhaust (QCE) regimes have been established as promising ELM-free scenarios. Here, the pressure gradient at the foot of the H-mode pedestal is reduced by a quasi-coherent mode, consistent with violation of the high-n ballooning mode stability limit there. This is suggestive that the EDA and QCE regimes have a common underlying physics origin. In the area of transport physics, full radius models for both L- and H-modes have been developed. These models predict energy confinement in AUG better than the commonly used global scaling laws, representing a large step towards the goal of predictive capability. A new momentum transport analysis framework has been developed that provides access to the intrinsic torque in the plasma core. In the field of exhaust, the X-Point Radiator (XPR), a cold and dense plasma region on closed flux surfaces close to the X-point, was described by an analytical model that provides an understanding of its formation as well as its stability, i.e., the conditions under which it transitions into a deleterious MARFE with the potential to result in a disruptive termination. With the XPR close to the divertor target, a new detached divertor concept, the compact radiative divertor, was developed. Here, the exhaust power is radiated before reaching the target, allowing close proximity of the X-point to the target. No limitations by the shallow field line angle due to the large flux expansion were observed, and sufficient compression of neutral density was demonstrated. With respect to the pumping of non-recycling impurities, the divertor enrichment was found to mainly depend on the ionisation energy of the impurity under consideration. In the area of MHD physics, analysis of the hot plasma core motion in sawtooth crashes showed good agreement with nonlinear 2-fluid simulations. This indicates that the fast reconnection observed in these events is adequately described including the pressure gradient and the electron inertia in the parallel Ohm’s law. Concerning disruption physics, a shattered pellet injection system was installed in collaboration with the ITER International Organisation. Thanks to the ability to vary the shard size distribution independently of the injection velocity, as well as its impurity admixture, it was possible to tailor the current quench rate, which is an important requirement for future large devices such as ITER. Progress was also made modelling the force reduction of VDEs induced by massive gas injection on AUG. The H-mode density limit was characterised in terms of safe operational space with a newly developed active feedback control method that allowed the stability boundary to be probed several times within a single discharge without inducing a disruptive termination. Regarding integrated operation scenarios, the role of density peaking in the confinement of the ITER baseline scenario (high plasma current) was clarified. The usual energy confinement scaling ITER98(p,y) does not capture this effect, but the more recent H20 scaling does, highlighting again the importance of developing adequate physics based models. Advanced tokamak scenarios, aiming at large non-inductive current fraction due to non-standard profiles of the safety factor in combination with high normalised plasma pressure were studied with a focus on their access conditions. A method to guide the approach of the targeted safety factor profiles was developed, and the conditions for achieving good confinement were clarified. Based on this, two types of advanced scenarios (‘hybrid’ and ‘elevated’ q-profile) were established on AUG and characterised concerning their plasma performance.

    DOI： 10.1088/1741-4326/ad249d

    Scopus

  • Mass dependency of high-wavenumber turbulence in a linear partially magnetized plasma

    Kawachi, Y; Sasaki, M; Nishizawa, T; Kosuga, Y; Terasaka, K; Inagaki, S; Yamada, T; Kasuya, N; Moon, C; Nagashima, Y; Fujisawa, A

    PHYSICS OF PLASMAS   31 ( 4 )   2024.4   （ ISSN:1070-664X eISSN:1089-7674 ）

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    Publisher：Physics of Plasmas  

    We investigated the mass dependency of the high-wavenumber turbulence, which occurs at scales smaller than the ion effective Larmor radius, in a partially magnetized plasma column. In this system, two different types of fluctuations were observed: one exhibiting a coherent discrete spectrum, while the other displaying a broadband continuous spectrum. The phase velocities of both types showed a similar mass dependency, approximately matching the ion sound velocity or electron diamagnetic drift velocity. Additionally, we found that the discrete spectrum has a peak interval frequency comparable to the ion cyclotron frequency, which is consistent with ion cyclotron ranges of fluctuations, including ion Bernstein waves.

    DOI： 10.1063/5.0187997

    Web of Science

    Scopus

  • A Method to Analyze Plasma Images Using Modified Fourier-Bessel Functions

    NISHIMURA Yuki, FUJISAWA Akihide, NAGASHIMA Yoshihiko, MOON Chanho, NISHIZAWA Takashi, KOBAYASHI Tatsuya, SHIMIZU Akihiro, TOKUZAWA Tokihiko, IDO Takeshi, NISHIMURA Daiki, KOBAYASHI Taiki

    Plasma and Fusion Research   19 ( 0 )   1201014 - 1201014   2024.3   （ ISSN:1880-6821 eISSN:18806821 ）

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    Language：English   Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research  

    <p>A new method is proposed to analyze plasma image of tomography using modified Fourier-Bessel Functions (FBF) instead of the original FBF analysis. The application of the method to an assumed plasma image shows that the difference between the original and the fitting image is improved considerably to that of FBF, owing to giving a better fitting inside the plasma and eliminating the ghost values outside the plasma, without any disadvantages in analysis of plasma structures and patterns.</p>

    DOI： 10.1585/pfr.19.1201014

    Web of Science

    Scopus

    CiNii Research

  • Velocity Field Estimation using Tomography in a Cylindrical Plasma

    Daiki NISHIMURA, Akihide FUJISAWA, Yoshihiko NAGASHIMA, Chanho MOON, Kotaro YAMASAKI, Takashi NISHIZAWA, Taiki KOBAYASHI, Tatsuya KOBAYASHI, Akihiro SHIMIZU, Tokihiko TOKUZAWA

    Plasma and Fusion Research   19   1201005 - 1201005   2024.1

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1585/pfr.19.1201005

  • Estimation of plasma parameter profiles and their derivatives from linear observations by using Gaussian processes Reviewed

    T Nishizawa, S Tokuda, T Kobayashi, K Tanaka, H Funaba, I Yamada, Y Takemura, T Tokuzawa, R Yasuhara, H Uehara, K Ida, H Takahashi, Y Kawachi, S Inagaki, S Kado, M Sasaki, A Fujisawa

    Plasma Physics and Controlled Fusion   65 ( 12 )   125006 - 125006   2023.11

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1361-6587/ad074a

  • Transition between continuous and discrete spectra of high-wavenumber turbulence in neutral gas pressure scan experiments on a linear magnetized plasma

    Yuichi Kawachi, Makoto Sasaki, Takashi Nishizawa, Yusuke Kosuga, Kenichiro Terasaka, Shigeru Inagaki, Takuma Yamada, Naohiro Kasuya, Chanho Moon, Yoshihiko Nagashima, Akihide Fujisawa

    Plasma Physics and Controlled Fusion   65 ( 11 )   115001 - 115001   2023.9

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1361-6587/acfbf7

  • Rotational movement analysis based on Fourier-rectangular function transform for cylindrical plasma Reviewed

    D. Nishimura, A. Fujisawa, K. Yamasaki, Y. Nagashima, C. Moon, T. Nishizawa, T.-K. Kobayashi, T. Kobayashi, A. Shimizu, T. Tokuzawa, T. Ido

    Journal of Applied Physics   134 ( 11 )   2023.9

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/5.0165318

  • Nonlinear simulation of resistive drift waves in cylindrical magnetized plasmas in the presence of symmetry breaking particle source Reviewed

    M. Sasaki, N. Kasuya, Y. Kawachi, T. Kobayashi, T. Nishizawa, H. Arakawa, T. Yamada, A. Fujisawa

    Physics of Plasmas   30 ( 8 )   2023.8

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/5.0150748

  • Simultaneous inference of multiple plasma parameter profiles by utilizing transport properties Reviewed

    Takashi Nishizawa

    Contributions to Plasma Physics   63 ( 5-6 )   2023.3

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1002/ctpp.202200150

  • Spatiotemporal dynamics of high-wavenumber turbulence in a basic laboratory plasma Reviewed

    Yuichi Kawachi, Makoto Sasaki, Yusuke Kosuga, Kenichiro Terasaka, Takashi Nishizawa, Takuma Yamada, Naohiro Kasuya, Chanho Moon, Shigeru Inagaki

    Scientific Reports   12 ( 1 )   2022.12

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1038/s41598-022-23559-1

  • Turbulence in the near scrape-off layer towards the L-mode density limit in ASDEX-Upgrade Reviewed

    G. Grenfell, P. Manz, G.D. Conway, T. Eich, J. Adamek, D. Brida, M. Komm, T. Nishizawa, M. Griener, B. Tal, U. Stroth

    Nuclear Materials and Energy   33   101277 - 101277   2022.10

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.nme.2022.101277

  • Characterizing the flow and turbulence structure near the last closed flux surface in L-mode plasmas of ASDEX Upgrade Reviewed

    T. Nishizawa, P. Manz, G. Grenfell, M. Griener, D. Wendler, D. Brida, D. M. Kriete, R. Dux, T. Kobayashi, M. Sasaki

    Physics of Plasmas   29 ( 7 )   072304 - 072304   2022.7

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/5.0098294

  • Non-parametric inference of impurity transport coefficients in the ASDEX Upgrade tokamak Reviewed

    T. Nishizawa, R. Dux, R.M. McDermott, F. Sciortino, M. Cavedon, C. Schuster, E. Wolfrum, U. von Toussaint, A.Jansen Van Vuuren, D.J. Cruz-Zabala, P. Cano-Megias, C. Moon, the ASDEX Upgrade Team

    Nuclear Fusion   62 ( 7 )   076021 - 076021   2022.7

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1741-4326/ac60e8

  • Experimental investigation of L- and H-mode detachment via the divertor Thomson scattering at ASDEX Upgrade Reviewed

    M. Cavedon, B. Kurzan, M. Bernert, D. Brida, R. Dux, M. Griener, S. Henderson, E. Huett, T. Nishizawa, T. Lunt, O. Pan, U. Stroth, M. Wischmeier, E. Wolfrum, the ASDEX Upgrade Team

    Nuclear Fusion   62 ( 6 )   066027 - 066027   2022.6

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1741-4326/ac6071

  • Edge turbulence measurements in L-mode and I-mode at ASDEX Upgrade Reviewed

    Physics of Plasmas   29 ( 5 )   052504 - 052504   2022.5

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/5.0088062

  • Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

    Pedersen, TS; Abramovic, I; Agostinetti, P; Torres, MA; Äkäslompolo, S; Belloso, JA; Aleynikov, P; Aleynikova, K; Alhashimi, M; Ali, A; Allen, N; Alonso, A; Anda, G; Andreeva, T; Angioni, C; Arkhipov, A; Arnold, A; Asad, W; Ascasibar, E; Aumeunier, MH; Avramidis, K; Aymerich, E; Baek, SG; Bähner, J; Baillod, A; Balden, M; Baldzuhn, J; Ballinger, S; Banduch, M; Bannmann, S; Navarro, AB; Barbui, T; Beidler, C; Belafdil, C; Bencze, A; Benndorf, A; Beurskens, M; Biedermann, C; Biletskyi, O; Blackwell, B; Blatzheim, M; Bluhm, T; Böckenhoff, D; Bongiovi, G; Borchardt, M; Borodin, D; Boscary, J; Bosch, H; Bosmann, T; Böswirth, B; Böttger, L; Bottino, A; Bozhenkov, S; Brakel, R; Brandt, C; Bräuer, T; Braune, H; Brezinsek, S; Brunner, K; Buller, S; Burhenn, R; Bussiahn, R; Buttenschön, B; Buzás, A; Bykov, V; Calvo, I; Mata, KC; Caminal, I; Cannas, B; Cappa, A; Carls, A; Carovani, F; Carr, M; Carralero, D; Carvalho, B; Casas, J; Castano-Bardawil, D; Castejon, F; Chaudhary, N; Chelis, I; Chomiczewska, A; Coenen, JW; Cole, M; Cordella, F; Corre, Y; Crombe, K; Cseh, G; Csillag, B; Damm, H; Day, C; de Baar, M; De la Cal, E; Degenkolbe, S; Demby, A; Denk, S; Dhard, C; Di Siena, A; Dinklage, A; Dittmar, T; Dreval, M; Drevlak, M; Drewelow, P; Drews, P; Dunai, D; Edlund, E; Effenberg, F; Ehrke, G; Endler, M; Ennis, DA; Escoto, FJ; Estrada, T; Fable, E; Fahrenkamp, N; Fanni, A; Faustin, J; Fellinger, J; Feng, Y; Figacz, W; Flom, E; Ford, O; Fornal, T; Frerichs, H; Freundt, S; Fuchert, G; Fukuyama, M; Füllenbach, F; Gantenbein, G; Gao, Y; Garcia, K; Regaña, JMG; Garcia-Cortes, I; Gaspar, J; Gates, DA; Geiger, J; Geiger, B; Giudicotti, L; González, A; Goriaev, A; Gradic, D; Grahl, M; Graves, JP; Green, J; Grelier, E; Greuner, H; Gross, S; Grote, H; Groth, M; Gruca, M; Grulke, O; Grün, M; Arnaiz, JG; Günter, S; Haak, V; Haas, M; Hacker, P; Hakola, A; Hallenbert, A; Hammond, K; Han, X; Hansen, SK; Harris, JH; Hartfuss, H; Hartmann, D; Hathiramani, D; Hatzky, R; Hawke, J; Hegedus, S; Hein, B; Heinemann, B; Helander, P; Henneberg, S; Hergenhahn, U; Hidalgo, C; Hindenlang, F; Hirsch, M; Höfel, U; Hollfeld, KP; Holtz, A; Hopf, D; Höschen, D; Houry, M; Howard, J; Huang, X; Hubeny, M; Hudson, S; Ida, K; Igitkhanov, Y; Igochine, V; Illy, S; Ionita-Schrittwieser, C; Isobe, M; Jablonski, S; Jagielski, B; Jakubowski, M; van Vuuren, AJ; Jelonnek, J; Jenko, F; Jensen, T; Jenzsch, H; Junghanns, P; Kaczmarczyk, J; Kallmeyer, J; Kamionka, U; Kandler, M; Kasilov, S; Kazakov, Y; Kennedy, D; Kharwandikar, A; Khokhlov, M; Kiefer, C; Killer, C; Kirschner, A; Kleiber, R; Klinger, T; Klose, S; Knauer, J; Knieps, A; Köchl, F; Kocsis, G; Kolesnichenko, YI; Könies, A; König, R; Kontula, J; Kornejew, P; Koschinsky, J; Kozulia, MM; Krämer-Flecken, A; Krampitz, R; Krause, M; Krawczyk, N; Kremeyer, T; Krier, L; Kriete, DM; Krychowiak, M; Ksiazek, I; Kubkowska, M; Kuczynski, M; Kühner, G; Kumar, A; Kurki-Suonio, T; Kwak, S; Landreman, M; Lang, PT; Langenberg, A; Laqua, HP; Laqua, H; Laube, R; Lazerson, S; Lewerentz, M; Li, C; Liang, Y; Linsmeier, C; Lion, J; Litnovsky, A; Liu, S; Lobsien, J; Loizu, J; Lore, J; Lorenz, A; Losada, U; Louche, F; Lunsford, R; Lutsenko, V; Machielsen, M; Mackel, F; Maisano-Brown, J; Maj, O; Makowski, D; Manduchi, G; Maragkoudakis, E; Marchuk, O; Marsen, S; Martines, E; Martinez-Fernandez, J; Marushchenko, M; Masuzaki, S; Maurer, D; Mayer, M; McCarthy, KJ; Mccormack, O; McNeely, P; Meister, H; Mendelevitch, B; Mendes, S; Merlo, A; Messian, A; Mielczarek, A; Mishchenko, O; Missal, B; Mitteau, R; Moiseenko, VE; Mollen, A; Moncada, V; Mönnich, T; Morisaki, T; Moseev, D; Motojima, G; Mulas, S; Mulsow, M; Nagel, M; Naujoks, D; Naulin, V; Neelis, T; Neilson, H; Neu, R; Neubauer, O; Neuner, U; Nicolai, D; Nielsen, SK; Niemann, H; Nishiza, T; Nishizawa, T; Nührenberg, C; Ochoukov, R; Oelmann, J; Offermanns, G; Ogawa, K; Okamura, S; Ölmanns, J; Ongena, J; Oosterbeek, J; Otte, M; Pablant, N; Alvarez, NP; Pandey, A; Pasch, E; Pavlichenko, R; Pavone, A; Pawelec, E; Pechstein, G; Pelka, G; Perseo, V; Peterson, B; Pilopp, D; Pingel, S; Pisano, F; Plöckl, B; Plunk, G; Pölöskei, P; Pompe, B; Popov, A; Porkolab, M; Proll, J; Pueschel, MJ; Puiatti, ME; Sitjes, AP; Purps, F; Rahbarnia, K; Rasmussen, J; Reiman, A; Reimold, F; Reisner, M; Reiter, D; Richou, M; Riedl, R; Riemann, J; Risse, K; Roberg-Clark, G; Rohde, V; Romazanov, J; Rondeshagen, D; Rong, P; Rudischhauser, L; Rummel, T; Rummel, K; Runov, A; Rust, N; Ryc, L; Salembier, P; Salewski, M; Sanchez, E; Satake, S; Satheeswaran, G; Schacht, J; Scharff, E; Schauer, F; Schilling, J; Schlisio, G; Schmid, K; Schmitt, J; Schmitz, O; Schneider, W; Schneider, M; Schneider, P; Schrittwieser, R; Schröder, T; Schröder, M; Schroeder, R; Schweer, B; Schwörer, D; Scott, E; Shanahan, B; Sias, G; Sichta, P; Singer, M; Sinha, P; Sipliä, S; Slaby, C; Sleczka, M; Smith, H; Smoniewski, J; Sonnendrücker, E; Spolaore, M; Spring, A; Stadler, R; Stange, T; Stepanov, I; Stephey, L; Stober, J; Stroth, U; Strumberger, E; Suzuki, C; Suzuki, Y; Svensson, J; Szabolics, T; Szepesi, T; Szücs, M; Tabarés, FL; Tamura, N; Tancetti, A; Tantos, C; Terry, J; Thienpondt, H; Thomsen, H; Thumm, M; Travere, JM; Traverso, P; Tretter, J; Trier, E; Mora, HT; Tsujimura, T; Turkin, Y; Tykhyi, A; Unterberg, B; van Eeten, P; van Milligen, BP; van Schoor, M; Vano, L; Varoutis, S; Vecsei, M; Vela, L; Velasco, JL; Vervier, M; Vianello, N; Viebke, H; Vilbrandt, R; Vogel, G; Vogt, N; Volkhausen, C; von Stechow, A; Wagner, F; Wang, E; Wang, H; Warmer, F; Wauters, T; Wegener, L; Wegner, T; Weir, G; Wenzel, U; White, A; Wilde, F; Wilms, F; Windisch, T; Winkler, M; Winter, A; Winters, V; Wolf, R; Wright, AM; Wurden, GA; Xanthopoulos, P; Xu, S; Yamada, H; Yamaguchi, H; Yokoyama, M; Yoshinuma, M; Yu, Q; Zamanov, M; Zanini, M; Zarnstorff, M; Zhang, D; Zhou, S; Zhu, J; Zhu, C; Zilker, M; Zocco, A; Zohm, H; Zoletnik, S; Zsuga, L

    NUCLEAR FUSION   62 ( 4 )   2022.4   （ ISSN:0029-5515 eISSN:1741-4326 ）

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    Publisher：Nuclear Fusion  

    We present recent highlights from the most recent operation phases of Wendelstein 7-X, the most advanced stellarator in the world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens of seconds. Pellet fueling allows for plasma phases with reduced ion-temperature-gradient turbulence, and during such phases, the overall confinement is so good (energy confinement times often exceeding 200 ms) that the attained density and temperature profiles would not have been possible in less optimized devices, since they would have had neoclassical transport losses exceeding the heating applied in W7-X. This provides proof that the reduction of neoclassical transport through magnetic field optimization is successful. W7-X plasmas generally show good impurity screening and high plasma purity, but there is evidence of longer impurity confinement times during turbulence-suppressed phases.

    DOI： 10.1088/1741-4326/ac2cf5

    Web of Science

    Scopus

  • Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development

    Stroth U., Aguiam D., Alessi E., Angioni C., Arden N., Parra R.A., Artigues V., Asunta O., Balden M., Bandaru V., Banon-Navarro A., Behler K., Bergmann A., Bergmann M., Bernardo J., Bernert M., Biancalani A., Bielajew R., Bilato R., Birkenmeier G., Blanken T., Bobkov V., Bock A., Body T., Bolzonella T., Bonanomi N., Bortolon A., Böswirth B., Bottereau C., Bottino A., Van Den Brand H., Brenzke M., Brezinsek S., Brida D., Brochard F., Bruhn C., Buchanan J., Buhler A., Burckhart A., Camenen Y., Cannas B., Megias P.C., Carlton D., Carr M., Carvalho P., Castaldo C., Cavedon M., Cazzaniga C., Challis C., Chankin A., Cianfarani C., Clairet F., Coda S., Coelho R., Coenen J.W., Colas L., Conway G., Costea S., Coster D., Cote T., Creely A.J., Croci G., Zabala D.J.C., Cseh G., Czarnecka A., Cziegler I., D'Arcangelo O., Molin A.D., David P., Day C., De Baar M., De Marné P., Delogu R., Denk S., Denner P., Di Siena A., Palacios Durán J.J.D., Dunai D., Drenik A., Dreval M., Drube R., Dunne M., Duval B.P., Dux R., Eich T., Elgeti S., Encheva A., Engelhardt K., Erdös B., Erofeev I., Esposito B., Fable E., Faitsch M., Fantz U., Farnik M., Faugel H., Felici F., Ficker O., Fietz S., Figueredo A.

    Nuclear Fusion   62 ( 4 )   2022.4   （ ISSN:00295515 ）

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    Publisher：Nuclear Fusion  

    An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low-Z impurity profiles. The L-H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β. The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts.

    DOI： 10.1088/1741-4326/ac207f

    Scopus

  • High-heat flux ball-pen probe head in ASDEX-Upgrade Reviewed

    G. Grenfell, J. Adamek, M. Komm, D. Brida, G. D. Conway, P. Manz, P. Tolias, T. Eich, D. Sestak, A. Herrmann, T. Nishizawa, U. Stroth

    Review of Scientific Instruments   93 ( 2 )   023507 - 023507   2022.2

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/5.0075846

  • Physics Exploitation of the new Divertor Thomson Scattering at ASDEX Upgrade

    Cavedon M., Dux R., Kurzan B., Bernert M., Brida D., Henderson S., Nishizawa T., Lunt T., Pan O., Reimold F., Stroth U., Wischmeier M., Wu H.

    48th EPS Conference on Plasma Physics, EPS 2022   2022

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    Publisher：48th EPS Conference on Plasma Physics, EPS 2022  

    Scopus

  • Linearized spectrum correlation analysis for thermal helium beam diagnostics Reviewed

    T. Nishizawa, M. Griener, R. Dux, G. Grenfell, D. Wendler, S. Kado, P. Manz, M. Cavedon

    Review of Scientific Instruments   92 ( 10 )   103501 - 103501   2021.10

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/5.0062436

  • Method for estimating the frequency-wavenumber resolved power spectrum density using the maximum entropy method for limited spatial points Reviewed

    T Kobayashi, T Nishizawa, M Sasaki, M Yoshinuma, K Ida

    Plasma Physics and Controlled Fusion   63 ( 4 )   045011 - 045011   2021.4

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1361-6587/abe024

  • Plasma parameter profile inference from limited data utilizing second-order derivative priors and physic-based constraints Reviewed

    T. Nishizawa, M. Cavedon, R. Dux, F. Reimold, U. von Toussaint

    Physics of Plasmas   28 ( 3 )   032504 - 032504   2021.3

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/5.0039011

  • Direct measurements of the 3D plasma velocity in single-helical-axis RFP plasmas Reviewed

    J. Boguski, M. D. Nornberg, U. Gupta, K. J. McCollam, A. F. Almagri, B. E. Chapman, D. Craig, T. Nishizawa, J. S. Sarff, C. R. Sovinec, P. W. Terry, Z. A. Xing

    Physics of Plasmas   28 ( 1 )   012510 - 012510   2021.1

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/5.0025696

  • Impact of resonant magnetic perturbations on zonal flows and microturbulence Reviewed

    Z.R. Williams, M.J. Pueschel, P.W. Terry, T. Nishizawa, D.M. Kriete, M.D. Nornberg, J.S. Sarff, G.R. McKee, D.M. Orlov, S.H. Nogami

    Nuclear Fusion   60 ( 9 )   096004 - 096004   2020.9

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1741-4326/ab9be7

  • Bayesian inference of particle source and sink in a closed-divertor using Balmer line spectroscopy Reviewed

    T Nishizawa, M Cavedon, F Reimold, R Dux, D Brida, H Wu

    Plasma Physics and Controlled Fusion   62 ( 8 )   085005 - 085005   2020.8

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1361-6587/ab9732

  • Effects of oscillating poloidal current drive on magnetic relaxation in the Madison Symmetric Torus reversed-field pinch Reviewed

    Zichao Li, K J McCollam, T Nishizawa, E Parke, J S Sarff, Z A Xing, Hong Li, Wandong Liu, Weixing Ding

    Plasma Physics and Controlled Fusion   61 ( 4 )   045004 - 045004   2019.4

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1361-6587/aaf9e0

  • Direct Measurement of a Toroidally Directed Zonal Flow in a Toroidal Plasma Reviewed

    Physical Review Letters   122 ( 10 )   2019.3

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/physrevlett.122.105001

  • Development of a multi-channel capacitive probe for electric field measurements with fine spatial and high time resolution Reviewed

    T. Nishizawa, A. F. Almagri, W. Goodman, S. Ohshima, J. S. Sarff

    Review of Scientific Instruments   89 ( 10 )   10J118 - 10J118   2018.10

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.5035093

  • Measurements of Impurity Transport Due to Drift-Wave Turbulence in a Toroidal Plasma Reviewed

    Physical Review Letters   121 ( 16 )   2018.10

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/physrevlett.121.165002

  • Dependence of Perpendicular Viscosity on Magnetic Fluctuations in a Stochastic Topology Reviewed

    Physical Review Letters   120 ( 22 )   2018.5

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/physrevlett.120.225002

  • Linearized spectrum correlation analysis for line emission measurements Reviewed

    T. Nishizawa, M. D. Nornberg, D. J. Den Hartog, J. S. Sarff

    Review of Scientific Instruments   88 ( 8 )   083513 - 083513   2017.8

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.4999450

  • Absolute wavelength calibration of a Doppler spectrometer with a custom Fabry-Perot optical system Reviewed

    M. M. Baltzer, D. Craig, D. J. Den Hartog, T. Nishizawa, M. D. Nornberg

    Review of Scientific Instruments   87 ( 11 )   11E509 - 11E509   2016.11

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.4955491

  • Upgrading a high-throughput spectrometer for high-frequency (<400 kHz) measurements Reviewed

    T. Nishizawa, M. D. Nornberg, D. J. Den Hartog, D. Craig

    Review of Scientific Instruments   87 ( 11 )   11E530 - 11E530   2016.11

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1063/1.4960073

  • Development of a Fast Timing Counter with a Monolithic MPPC Array Reviewed

    T. Nishizawa, Y. Fujii, H. Kanda, M. Kaneta, Y. Kasai, J. Kusaka, K. Maeda, S. Nagao, S. N. Nakamura, K. Tsukada, F. Yamamoto

    IEEE Transactions on Nuclear Science   61 ( 3 )   1278 - 1283   2014.6

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    Language：Others   Publishing type：Research paper (scientific journal)  

    DOI： 10.1109/tns.2014.2321657

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Professional Memberships

  • physical society of Japan

  • American Physical Society

Research Projects

  • 磁場閉じ込め高温プラズマの乱流輸送に及ぼす不純物の影響の定量的解明 研究課題

    Grant number：23KK0054  2023 - 2027

    日本学術振興会  科学研究費助成事業  国際共同研究強化(B)

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    Authorship：Coinvestigator(s)  Grant type：Scientific research funding

  • 大型装置への外挿を目的とした局所ヘリシティ入射法によるプラズマ立ち上げの実証

    Grant number：23K13085  2023 - 2025

    日本学術振興会  科学研究費助成事業  若手研究

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    Authorship：Principal investigator  Grant type：Scientific research funding

  • PLATO, PANTA

    2022.6

  • 局所ヘリシティ入射法によるプラズマ立ち上げ時の自己組織化過程の解明

    Grant number：22K20358  2022 - 2023

    日本学術振興会  科学研究費助成事業  研究活動スタート支援

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    Authorship：Principal investigator  Grant type：Scientific research funding

  • プラズマ乱流におけるスケール混合を伴う構造形成

    Grant number：21K03509  2021.4 - 2025.3

    科学研究費助成事業  基盤研究(C)

    佐々木 真, 西澤 敬之

    　 More details

    Grant type：Scientific research funding

    磁場閉じ込めプラズマには背景流れが存在し、乱流輸送に大きな影響を与えることで、多様なプラズマ分布変形を引き起こし、輸送障壁や階段状分布等の凸凹な分布を示す。このような凸凹分布の空間スケールは乱流の波長スケールと同程度となり、すなわちスケール混合が起こる。本研究では、乱流とプラズマ分布のスケール混合過程に焦点を当て、アバランチや階段状分布・輸送障壁を包括する大域的凸凹分布の選択則を明らかにする。従来のスケール分離を仮定せずに、簡約流体モデルに基づく理論解析と乱流シミュレーションとを組み合わせる事で、大域的分布予測・制御指針を得る事を目指す。

    CiNii Research

Class subject

  • プラズマ理工学演習

    2023.10 - 2024.3   Second semester

  • プラズマ理工学演習

    2022.10 - 2023.3   Second semester