Tomoya TATSUNO
| Department of Computer and Network Engineering | Professor |
| Cluster I (Informatics and Computer Engineering) | Professor |
Researcher Information
Research Keyword
Career
- Apr. 2022 - Present
The University of Electro-Communications, Professor - Jul. 2011 - Mar. 2022
University of Electro-Communications, Associate Professor - Aug. 2005 - Jun. 2011
University of Maryland, Assistant Research Scientist - Aug. 2003 - Aug. 2005
University of Maryland, Research Associate - Apr. 1999 - Aug. 2003
University of Tokyo, Assistant
Research Activity Information
Paper
- Freely decaying turbulence in two-dimensional electrostatic gyrokinetics
T. Tatsuno; G. G. Plunk; M. Barnes; W. Dorland; G. G. Howes; R. Numata
PHYSICS OF PLASMAS, 19, 12, 122305, Dec. 2012, Peer-reviwed
Scientific journal, English - Considering fluctuation energy as a measure of gyrokinetic turbulence
G. G. Plunk; T. Tatsuno; W. Dorland
NEW JOURNAL OF PHYSICS, 14, 10, 103030, Oct. 2012, Peer-reviwed
Scientific journal, English - Gyrokinetic simulations of the tearing instability
Ryusuke Numata; William Dorland; Gregory G. Howes; Nuno F. Loureiro; Barrett N. Rogers; Tomoya Tatsuno
PHYSICS OF PLASMAS, 18, 11, 112106, Nov. 2011, Peer-reviwed
Scientific journal, English - Gyrokinetic Simulations of Solar Wind Turbulence from Ion to Electron Scales
G. G. Howes; J. M. TenBarge; W. Dorland; E. Quataert; A. A. Schekochihin; R. Numata; T. Tatsuno
PHYSICAL REVIEW LETTERS, 107, 3, 035004, Jul. 2011, Peer-reviwed
Scientific journal, English - Energy Transfer and Dual Cascade in Kinetic Magnetized Plasma Turbulence
G. G. Plunk; T. Tatsuno
PHYSICAL REVIEW LETTERS, 106, 16, 165003, Apr. 2011, Peer-reviwed
Scientific journal, English - AstroGK: Astrophysical gyrokinetics code
Ryusuke Numata; Gregory G. Howes; Tomoya Tatsuno; Michael Barnes; William Dorland
JOURNAL OF COMPUTATIONAL PHYSICS, 229, 24, 9347-9372, Dec. 2010, Peer-reviwed
Scientific journal, English - Numerical modeling of Large Plasma Device Alfveacuten wave experiments using AstroGK
Kevin D. Nielson; Gregory G. Howes; Tomoya Tatsuno; Ryusuke Numata; William Dorland
PHYSICS OF PLASMAS, 17, 2, Feb. 2010, Peer-reviwed
Scientific journal, English - Nonlinear Phase Mixing and Phase-Space Cascade of Entropy in Gyrokinetic Plasma Turbulence
T. Tatsuno; W. Dorland; A. A. Schekochihin; G. G. Plunk; M. Barnes; S. C. Cowley; G. G. Howes
PHYSICAL REVIEW LETTERS, 103, 1, 015003, Jul. 2009, Peer-reviwed
Scientific journal, English - Magneto-flow instability in symmetric field profiles
T. Tatsuno; W. Dorland
PHYSICS OF PLASMAS, 13, 9, 092107, Sep. 2006, Peer-reviwed
Scientific journal, English - Statistical characterization of the interchange-instability spectrum of a separable ideal-magnetohydrodynamic model system
RL Dewar; T Tatsuno; Z Yoshida; C Nuhrenberg; BF McMillan
PHYSICAL REVIEW E, 70, 6, 066409-066409, Dec. 2004, Peer-reviwed
Scientific journal, English - Degenerate continuous spectra producing localized secular instability - an example in a non-neutral plasma
M Hirota; T Tatsuno; Z Yoshida
JOURNAL OF PLASMA PHYSICS, 69, 397-412, Oct. 2003, Peer-reviwed
Scientific journal, English - Destabilizing effect of shear flow - beyond Kelvin-Helmholtz instability
T Tatsuno; M Hirota; A Ito; S Kondoh; Z Yoshida; SM Mahajan
PLASMA PHYSICS, 669, 666-669, 2003, Peer-reviwed
International conference proceedings, English - Secular behavior of electrostatic Kelvin-Helmholtz (diocotron) modes coupled with plasma oscillations
M Hirota; T Tatsuno; S Kondoh; Z Yoshida
PHYSICS OF PLASMAS, 9, 4, 1177-1184, Apr. 2002, Peer-reviwed
Scientific journal, English - Magnetic shear stabilization of diocotron instability
S Kondoh; T Tatsuno; Z Yoshida
NON-NEUTRAL PLASMA PHYSICS IV, 606, 311-316, 2002, Peer-reviwed
International conference proceedings, English - Stabilization effect of magnetic shear on the diocotron instability
S Kondoh; T Tatsuno; Z Yoshida
PHYSICS OF PLASMAS, 8, 6, 2635-2640, Jun. 2001, Peer-reviwed
Scientific journal, English - Transient phenomena and secularity of linear interchange instabilities with shear flows in homogeneous magnetic field plasmas
T Tatsuno; F Volponi; Z Yoshida
PHYSICS OF PLASMAS, 8, 2, 399-406, Feb. 2001, Peer-reviwed
Scientific journal, English - Shear-flow induced stabilization of kinklike modes
F Volponi; Z Yoshida; T Tatsuno
PHYSICS OF PLASMAS, 7, 6, 2314-2319, Jun. 2000, Peer-reviwed
Scientific journal, English
MISC
- 位相空間における磁化プラズマの2次元乱流解析
龍野智哉
Sep. 2012, 日本物理学会誌, 67, 9, 614, 640-644, Japanese, Peer-reviwed, Introduction other - Parallel simulation of phase-space turbulence in magnetized plasmas
龍野 智哉
宇宙空間や実験室に見られる，磁化された完全電離プラズマのダイナミクスを位相空間でシミュレーションする数値コード AstroGK の並列化に関する概要と，近年行われた位相空間乱流に関するシミュレーション結果を概観した．This document summarizes the parallelization scheme of numerical code AstroGK which simulates the dynamics of fully-ionized, magnetized plasmas seen in space and laboratory; and recent simulation results made for phase-space turbulence., 25 May 2012, 研究報告ハイパフォーマンスコンピューティング（HPC）, 2012, 8, 1-4, Japanese, 110009453402, AN10463942
Courses
Affiliated academic society
Research Themes
- Experimental Studies on the High-beta Equilibrium and Stability of Rapidly Flowing Plasma Produced in Toroidal Non-neutral Plasma Trap
YOSHIDA Zensho; FURUKAWA Masaru; SAITOH Haruhiko; OGAWA Yuichi; MORIKAWA Junji
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, The University of Tokyo, Grant-in-Aid for Scientific Research (S), We have studied the self-organization mechanism in flowing plasmas to explore the diversity of structures created in space and astronomical systems, and also examined the applicability of the high-beta equilibrium for advanced-fusion concept. 1.Results of Theoretical Studies We have developed some innovative methods for the analysis of equilibria and stability of flowing plasmas. Unlike the conventional theories of stationary (non-flowing) plasmas, the analysis of flowing plasmas may not invoke the well-known methods of spectral decomposition or energy principle. Analyzing the topological singularities of the non-canonical Hamiltonian formalisms, we have succeeded to characterize the basic vertical structures of flow-field coupling in terms of Casimir invariants (helicities). The corresponding variational principle yields a Lyapunov function, whose coercivity warrants the stability of the "Beltrami fields", the minimizer of the variational principle. The theory has been applied to explain the structural instabilities in solar corona, high-beta equilibria in Jupiter's magnetosphere, as well as new-type of flowing equilibria in Proto-RT and RT-1 devices. 2.Results of Experimental Studies We have demonstrated stable formation of super-sonic (Mach number > 5) rotating plasma in the Proto-RT Device. The Proto-RT device can confine a non-neutral (pure electron) plasma in a "magnetosphere-like" configuration. A non-neutral plasma produces a flowing (spinning) equilibrium by its self-electric field. By applying an internal electric field in a quasi-neutral plasma, we can achieve a similar flowing plasma. We have established a unified understanding of non-neutral and flowing plasmas : (1)We have demonstrated stable confinement of non-neutral plasma in a magnetic-surface configuration,; (2)By applying a radial electric field, we have demonstrated the self-organization of stable super-sonic flowing plasma ; (3)We have demonstrated the production of a new branch of equilibrium by the effect of fast flow ; (4)We have developed new technologies to construct magnetosphere-like plasma confinement device., 14102033
2002 - 2006 - プラズマにおける流れの安定化―不安定化効果の競合
龍野 智哉
日本学術振興会, 科学研究費助成事業, 東京大学, 若手研究(B), 流れのあるプラズマに関する安定性理論の研究を行った. プラズマ中の平行流のうち,流れによって平衡が不安定化される例としてKelvin-Helmholtz不安定性が良く知られているが,流れそのものが安定であっても,それを付加することによりプラズマ中の潜在的な不安定性が更に不安定化される場合があることを示し,その結果をPhysics of Plasmasに発表した[Destabilizing effect of plane Couette flow, Phys. Plasmas 10,2278(2003)]. Couette流は空間的に線形なプロファイルを持つ流れであり,その空間的な不均一性により,従来まではモードを引き伸ばすことで不安定性を抑制する働きがあると理解されてきた.ところが,我々が今回示した例では,プラズマ中の波(正確にはAlfvenと呼ばれる横波)には流れの引き伸ばし効果に逆らって渦度を運ぶ働きがあり,背景流はそのAlfven波に打ち勝つほど速くない限り引き神ばし効果は弱く,却って元々あった磁力線の曲げによる安定化効果をキャンセルするために不安定性を助長する. 中性流体におけるKelvin-Helmholtz不安定性について,Rayleighの表面波モデルに対するスペクトル構造の詳細な解析を行った.このモデルは区分的に線形なプロファイルの背景流を仮定した簡単なものであるが,我々の構築したスペクトル分解理論により,連続スペクトルと点スペクトルとの間に周波数縮退が存在することが示されている.このモデルに対して,今回の研究では流れのプロファイルが線形からずれた場合,点スペクトルが連続スペクトルに転移することを示した.この転移に伴う時間挙動は,漸近的には大きな変化をもたらすが,ある時間までは線形流の場合とそれほど変わらないと想像される.また非中性プラズマにおけるダイオコトロン不安定性を考えれば,上記の周波数縮退にプラズマ振動がカップリングすることにより代数的な不安定性が生じることを示し,その結果を国際会議International Congress on Industrial and Applied Mathematics(Sydney,2003)において口頭発表した. これらの知見をまとめてレビュー論文を執筆し,プラズマ・核融合学会誌に投稿した(Stabilizing and destabilizing effect of shear flow,プラズマ・核融合学会誌に採録が決定)., 15740323
2003 - 2004 - 流れのあるプラズマに関する安定性理論の数学的基礎
龍野 智哉
日本学術振興会, 科学研究費助成事業, 東京大学, 奨励研究(A), 流れのあるプラズマに関する安定性理論の研究を行った. 1887年にKelvinによって発表された解析手法が,線形プロファイルをもつ流れのあるプラズマについて一般解を与えることを数学的に示し,その手法に基づいて磁場閉じ込めプラズマ中の電流駆動不安定性,及び圧力駆動不安定性の解析を行った.流れによって作用素がエルミートでない場合にも,プラズマの線形運動が変形していくモードに分解できることを示した.これらのモードはエルミート作用素に対する指数関数から大きく外れ,過渡的な成長を示すと共に,漸近的には時間について代数的に減衰することを示した.すなわち,流れの効果がプラズマ中に内在する不安定性を安定化させるわけである. また表面波モデルを用いたKelvin-Helmholtz不安定性の解析において,従来見過ごされてきた連続スペクトルと点スペクトルとの非エルミートな相互作用による,共鳴現象が存在することを示し,数学的なスペクトル理論を構築した.非中性プラズマにおけるdiocotron不安定性についても解析を行った.固有値解析では流れによる不安定性が磁気シアーによって安定化されることを示した.初期値問題を数値的に解くと,作用素の非エルミート性から連続スペクトル同士の周波数縮退による共鳴現象が起こり,空間的に局在化する代数的な密度揺動の成長が起こることを示した. 次に,相対論的速度をもつプラズマについて,高周波の波動は1次元縞状のソリトン解をもつ.これは中性流体において有名なKelvin-Helmholtz不安定性に類似した不安定性によって2次元に崩壊するが,その際に角運動量を生成する.この2次元解は非常に安定であり,それらが何らかの理由である距離以上に離れると,その角運動量は保存される.不安定性の非線形発展に関しても数値計算を行い,実際に縞状ソリトンから2次元の渦ソリトンの形成まで,時間発展を追うことによって角運動量の生成が起こることを示した.この研究に関してさらに論文を執筆中である.これは応用上,初期宇宙の角運動量形成に関連がある解として興味深いものである., 12780353
2000 - 2001 - Kinetic Effects on Self-Organization in Plasma
YOSHIDA Zensho; TATSUNO Tomoya; HIMURA Haruhiko; OGAWA Yuichi; MORIKAWA Junji
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, The University of Tokyo, Grant-in-Aid for Scientific Research (B)., To explore innovative concepts of fusion plasma confinement, especially in the high-beta regime that can host the D-3He advanced fusion, we have to develop a sound understanding on the physics of relaxation that self-organizes the most preferable structure in the plasma. The theory of the Taylor relaxed states succeeded to explain the self-organization of the reversed-field pinch (RFP) and ultra-low-q (ULQ) plasmas. In the present research, we have made a considerable generalization of the self-organization theory through the study of kinetic (particle dynamics) and flow effects. The results are summarized as follows ; (1) When a plasma has a macroscopic non-neutral charge, the self-electric field yields a strong rotating flow. The two-fluid model provides a self-consistent description of the relaxed states with a strong flow. A variety of interesting structures can be cast in the model of double Beltrami fields ; (2) The particle motion becomes chaotic in a strongly inhomogeneous electromagnetic field, resulting in a rapid production of the kinetic entropy. As a macroscopif effect of the chaos, the resistive dissipation is much enhanced, which accounts for the anomalous resistance in the magnetic reconnection process of the self-organization., 10044130
1998 - 2000 - Toroidal Magnetic Confinement of Non-neutral Plasmas
YOSHIDA Zensho; TATSUNO Tomoya; HIMURA Haruhiko; OGAWA Yuichi; MORIKAWA Junji
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, The University of Tokyo, Grant-in-Aid for Scientific Research (A)., A new method of producing non-neutral plasmas has been developed with introducing an innovative scheme of injecting particles into a toroidal magnetic shear configuration. This method can be applied to various particle traps, as well as an ultra-high-beta fusion device that is suitable for advanced fusion. Unique features in this concept, in comparison with other conventional electric-field traps (such as the Penning trap), are summarized as follows ; (1) This pure magnetic confinement device can trap very high-energy particles directly ; (2) Continuous injection of particles enables to produce a high-density (up to the Brillouin limit) plasma ; (3) Multi-species particles with opposite charges can be confined simultaneously. The key issues of development were (A) the application of magnetic shear to stabilize the plasma and (B) the production of the chaos-induced collision-less diffusion to inject particles into the trapping region. Using this non-neutral plasma system, we have studied (I) the new-type of relaxed state in a plasma with an intense shear flow, (II) the anomalous diffusion and resistance induced by the chaos of particle motion in magnetic null region, (III) the non-Hermitian dynamics of vortices in a shear flow, and (IV) magnetic shear stabilization of electrostatic instabilities., 09308011
1997 - 2000
