| 1. |
M Scholer, S Matsukiyo, Nonstationarity of quasi-perpendicular shocks: a comparison of full particle simulations with different ion to electron mass ratio, ANNALES GEOPHYSICAE, Vol.22, No.7, pp.2345-2353, 2004.07, We have performed 3 one-dimensional full particle electromagnetic simulations of a quasi-perpendicular shock with the same Alfven Mach number M-A=4.5, shock normal - magnetic field angle Theta(Bn)=87degrees, and ion and electron beta (particle to magnetic field pressure) of 0.05, but with different ion to electron mass ratios (m(i)/m(e)=80, 400, 1840). At high ion beta it has been shown previously that the shock is steady. At low ion beta, as in the present simulations, the shock periodically reforms itself.. However, whereas at unrealistically low mass ratios the reformation is due to accumulation of specularly reflected particles at the upstream edge of the foot, at the realistic mass ratio the modified two-stream instability between the incoming solar wind ions and solar wind electrons leads to ion phase mixing and thermalization. The reformation process is thereby considerably modified. At the lowest mass ratio the Buneman instability between the solar wind electrons and the reflected ions is excited, which is stabilized at higher mass ratios.. |
| 2. |
Y. Kuramitsu, S. Matsukiyo, S. Isayama, D. Harada, T. Oyama, R. Fujino, Y. Sakawa, T. Morita, Y. Yamaura, T. Ishikawa, T. Moritaka, T. Sano, K. Tomita, R. Shimoda, Y. Sato, K. Uchino, A. Pelka, R. Crowston, N. Woolsey, G. Gregori, M. Koenig, D. W. Yuan, C. L. Yin, Y. T. Li, K. Zhang, J. Y. Zhong, F. L. Wang, N. Ohnishi, K. Nagamine, H. Yoneda, H. Takabe, Spherical shock in the presence of an external magnetic field, 8TH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS (IFSA 2013), 10.1088/1742-6596/688/1/012056, Vol.688, 2016.04, We investigate spherical collisionless shocks in the presence of an external magnetic field. Spherical collisionless shocks are common resultant of interactions between a expanding plasma and a surrounding plasma, such as the solar wind, stellar winds, and supernova remnants. Anisotropies often observed in shock propagations and their emissions, and it is widely believed a magnetic field plays a major role. Since the local observations of magnetic fields in astrophysical plasmas are not accessible, laboratory experiments provide unique capability to investigate such phenomena. We model the spherical shocks in the universe by irradiating a solid spherical target surrounded by a plasma in the presence of a magnetic field. We present preliminary results obtained by shadowgraphy.. |
| 3. |
S Matsukiyo, T Hada, M Nambu, J Sakai, Comparison between the Landau and cyclotron resonances in the electron beam-plasma interactions, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 10.1143/JPSJ.68.1049, Vol.68, No.3, pp.1049-1054, 1999.03, It is well-known that a cool field-aligned electron beam streaming in a plasma can destabilize electrostatic waves, in the frequency ranges of 0 < omega < min(Omega(e), omega(p)) and max(Omega(e), omega(p)) < omega < omega(uh), where omega(p), Omega(e), and omega(uh) are the plasma, the electron cyclotron, and the upper-hybrid frequencies. respectively. Although both the Landau and cyclotron resonances lead to the generation of the waves, not much attention has been paid to the wave generation via the cyclotron resonance. In this paper we compare the two types of interactions for both non-relativistic and relativistic electron beams by considering a simple plasma model which consists of main and beam electrons and background ions. The plasma is charge neutral and current carrying. The linear theory based on this model predicts that, when the electron beams are non-relativistic, the waves are generated predominantly via, the Landau interaction for a wide range of plasma parameters, except for a limited parameter regime with cool main electrons, Omega(e)/omega(p) > 1, and at oblique propagation angles. On the other hand, when the beam electrons have relativisitic drift momentum, the cyclotron interaction becomes more important than the Landau interaction.. |
| 4. |
S Matsukiyo, T Hada, Nonlinear evolution of electromagnetic waves driven by the relativistic ring distribution, PHYSICS OF PLASMAS, 10.1063/1.1431593, Vol.9, No.2, pp.649-661, 2002.02, Relativistic ring distribution of plasma particles generates electromagnetic waves via the relativistic cyclotron resonance. The long time evolution of this so-called cyclotron maser instability at null wave number (k=0) is studied in detail, by performing particle simulations using a plasma which consists of relativistic ring electrons, background positrons, and background electrons. The linear and nonlinear stages of the system evolution are discussed for both gyrotropic and nongyrotropic ring distributions. The linear theory predicts that, when the initial ring energy is strongly relativistic, there appears a critical initial ring momentum at which the system is marginally stable. Numerical simulations show, however, that the system is nonlinearly unstable even when the initial ring momentum exceeds the critical momentum. The final saturation level of the wave energy is obtained analytically. (C) 2002 American Institute of Physics.. |
| 5. |
M Scholer, Shinohara, I, S Matsukiyo, Quasi-perpendicular shocks: Length scale of the cross-shock potential, shock reformation, and implication for shock surfing, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2002JA009515, Vol.108, No.A1, p.SSH 4-1, 2003.01, One-dimensional (1-D) full particle simulations of almost perpendicular supercritical collisionless shocks are presented. The ratio of electron plasma frequency omega(pe) to gyrofrequency Omega(ce), the ion to electron mass ratio, and the ion and electron beta (beta = plasma to magnetic field pressure) have been varied. Due to the accumulation of specularly reflected ions upstream of the shock, ramp shocks can reform on timescales of the gyroperiod in the ramp magnetic field. Self-reformation is not a low omega(pe)/Omega(ce) process but occurs also in (omega(pe)/Omega(ce))(2) >> low beta simulations. Self-reformation also occurs in low ion b runs with an ion to electron mass ratio m(i)/m(e) = 1840. However, in the realistic mass ratio runs, an electromagnetic instability is excited in the foot of the shock, and the shock profile is considerably changed compared to lower mass ratio runs. Linear analysis based on three-fluid theory (incident ions, reflected ions, and electrons) indicates that the instability is a modified two-stream instability between the decelerated solar wind electrons and the solar wind ions on the whistler mode branch. In the reforming low ion b shocks, part of the potential drop occurs at times across the foot, and part of the potential (similar to40%) occurs over a few (similar to4) electron inertial lengths in the steepened up ramp. Self-reformation is a low ion beta process and disappears for a Mach 4.5 shock at/or above beta(i) approximate to0.4. It is argued that the ion thermal velocity has to be an order of magnitude smaller than the shock velocity in order for reformation to occur. Since according to these simulations only part of the potential drop occurs for relatively short times over a few electron inertial lengths, it is concluded that coherent shock surfing is not an efficient acceleration mechanism for pickup ions at the low beta heliospheric termination shock.. |
| 6. |
S. Matsukiyo, T. Hada, Parametric instabilities of circularly polarized Alfvén waves in a relativistic electron-positron plasma, Physical Review E, 10.1103/PhysRevE.67.046406, Vol.67, No.4, p.046406, 2003.04. |
| 7. |
S Matsukiyo, M Scholer, Modified two-stream instability in the foot of high Mach number quasi-perpendicular shocks, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2003JA010080, Vol.108, No.A12, p.SMP 19-1, 2003.12, The modified two-stream instability in the foot of supercritical quasi-perpendicular shock wave is investigated. A linear analysis shows that the instability can sufficiently grow during the shock reformation cycle for the case of a realistic ion to electron mass ratio. The wave-particle interactions of the Landau type of both the electrons and ions are essential in a finite beta plasma and lead to a reduction of the growth rate with increasing beta. The magnetic polarization in terms of wavevector is also analyzed. Additional one-dimensional full-particle electromagnetic simulations in a periodic system reveal some important nonlinear wave properties. The wave spectra indicate a lower cascade due to wave-wave interactions. The parallel phase space distribution of electrons correlates well with the wave profile of the magnetic field component perpendicular to both the ambient magnetic field and the wavevector. The nonlinearly generated waves lead to electron heating parallel to the magnetic field.. |
| 8. |
S Matsukiyo, RA Treumann, M Scholer, Coherent waveforms in the auroral upward current region, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2004JA010477, Vol.109, No.A6, p.A06212, 2004.06, With the help of one-dimensional particle-in-cell simulations we show that observations of high-frequency electric wave spectra in the auroral upward current region can be reproduced. Using distribution functions suggested by the measurements, we find that in the nonlinear state, ion acoustic waves and electron two-stream (Langmuir) waves dominate the spectrum. In the absence of cold electrons, electron acoustic waves are not excited initially but appear only at a late time. They are the result of the formation of a two-temperature electron plasma by nonlinear interactions when all other instabilities have saturated. However, owing to the weakness of these electron acoustic waves, they are less important for the formation of electron holes and affect the particle dynamics much less than the two-stream instability.. |
| 9. |
S Matsukiyo, M Scholer, On microinstabilities in the foot of high Mach number perpendicular shocks, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 10.1029/2005JA011409, Vol.111, No.A6, p.A06104, 2006.06, [ 1] Microinstabilities excited in the foot of a supercritical perpendicular shock wave are investigated. A two-dimensional full particle simulation with periodic boundary conditions in both directions using the physical ion to electron mass ratio is performed as a proxy for the foot region where incoming and specularly reflected ions overlap. The simulation shows that six types of different instabilities are excited in a time period shorter than ion gyroperiod of the reflected ions. The most dominant instability is the modified two-stream instability, which leads to strong parallel electron heating through a so-called two step instability and to ion phase space holes.. |
| 10. |
Y. Nariyuki, S. Matsukiyo, T. Hada, Parametric instabilities of large-amplitude parallel propagating Alfven waves: 2D PIC simulation, NEW JOURNAL OF PHYSICS, 10.1088/1367-2630/10/8/083004, Vol.10, No.8, p.083004, 2008.08, We discuss the parametric instabilities of large-amplitude parallel propagating Alfven waves using the 2D PIC simulation code. First, we confirmed the results from a previous study (Sakai et al 2005 New J. Phys. 7 233) that the electrons are heated due to the modified two-stream instability and that the ions are heated by the parallel propagating ion acoustic waves. However, although the past study argued that such parallel propagating longitudinal waves are excited by transverse modulation of the parent Alfven wave, we consider these waves are more likely to be generated by the usual, parallel decay instability. Further, we performed other simulation runs with different polarization of the parent Alfven waves or different ion thermal velocity. Numerical results suggest that electron heating by the modified two-stream instability due to the large amplitude Alfven waves is unimportant with most parameter sets.. |
| 11. |
S. Matsukiyo, T. Hada, RELATIVISTIC PARTICLE ACCELERATION IN DEVELOPING ALFVEN TURBULENCE, ASTROPHYSICAL JOURNAL, 10.1088/0004-637X/692/2/1004, Vol.692, No.2, pp.1004-1012, 2009.02, A new particle acceleration process in a developing Alfven turbulence in the course of successive parametric instabilities of a relativistic pair plasma is investigated by utilizing one-dimensional electromagnetic full particle code. Coherent wave-particle interactions result in efficient particle acceleration leading to a power-law-like energy distribution function. In the simulation, high-energy particles having large relativistic masses are preferentially accelerated as the turbulence spectrum evolves in time. The main acceleration mechanism is simultaneous relativistic resonance between a particle and two different waves. An analytical expression of maximum attainable energy in such wave-particle interactions is derived.. |
| 12. |
Shuichi Matsukiyo, Mach number dependence of electron heating in high Mach number quasiperpendicular shocks, PHYSICS OF PLASMAS, 10.1063/1.3372137, Vol.17, No.4, p.042901, 2010.04, The efficiency of electron heating through microinstabilities generated in the transition region of a quasiperpendicular shock for a wide range of Mach numbers is investigated by utilizing particle-in-cell (PIC) simulation and model analyses. In the model analyses saturation levels of effective electron temperature as a result of microinstabilities are estimated from an extended quasilinear (trapping) analysis for relatively low (high) Mach number shocks. Here, modified two-stream instability (MTSI) is assumed to become dominant in low Mach number regime, while Buneman instability (BI) is assumed to become dominant in high Mach number regime. It is revealed that Mach number dependence of the effective electron temperature in the MTSI dominant case is essentially different from that in the BI dominant case. The effective electron temperature through the MTSI does not depend much on the Mach number, although that through the BI increases with the Mach number as in the past studies. The results are confirmed to be consistent with the PIC simulations both in qualitative and quantitative levels. The model analyses predict that a critical Mach number, above which a steep rise in electron heating rate occurs, may arise at the Mach number of a few tens.. |
| 13. |
高出力レーザーによって生成された高速対向プラズマ流による無衝突衝撃波の生成. |
| 14. |
高出力レーザーを用いたプラズマジェットのコリメーション現象の研究. |
| 15. |
高出力レーザー生成プラズマ及び衝撃波のターゲット材質依存性について. |
| 16. |
29pEA-1 Experimental study on high Mach number collisionless shocks. |
| 17. |
29aEA-14 PIC simulation on the heliospheric termination shock. |
| 18. |
29aEA-10 Initial particle acceleration in collisionless shocks. |
| 19. |
Results of laser experiments for collisionless shocks. |
| 20. |
Theories on the production of high Mach number collisionless shocks. |
| 21. |
高出力レーザー生成無衝突衝撃波のトムソン散乱計測. |
| 22. |
超音速対向プラズマ流による無衝突衝撃波の生成. |
| 23. |
レーザー生成プラズマ中における磁場の計測. |
| 24. |
レーザー生成プラズマと外部磁場を用いた磁気リコネクションの研究. |
| 25. |
超音速対向プラズマ流による無衝突衝撃波の生成. |
| 26. |
磁化プラズマ中を伝播する低マッハ数の無衝突衝撃波の生成実験. |
| 27. |
協同的トムソン散乱法による無衝突衝撃波の研究. |
| 28. |
レーザー生成プラズマと外部磁場を用いた磁場リコネクションの研究. |
| 29. |
高出力レーザーを用いたプラズマ中衝撃波における磁場増幅モデル実験とその解析 II. |
| 30. |
超音速対向プラズマ流による無衝突衝撃波の生成. |
| 31. |
磁化プラズマ中を伝播する無衝突衝撃波の生成実験:2015年度の実験結果. |
| 32. |
磁化プラズマ中を伝播する低マッハ数の無衝突衝撃波の生成実験. |
| 33. |
無衝突衝撃波研究のための新規協同トムソン散乱システムの開発. |
| 34. |
Local Interactions between Collisionless Shock and Plasma : Waves, Multi-Scale Physics, Particle Acceleration/Heating. |
| 35. |
大型レーザー生成プラズマ中衝撃波における磁場増幅のモデル実験. |
| 36. |
磁化プラズマ中を伝播する低マッハ数の無衝突衝撃波の生成実験. |
| 37. |
N. Khasanah, C. W. Peng, C. H. Chen, T. Y. Huang, N. Bolouki, T. Moritaka, Y. Hara, H. Shimogawara, T. Sano, Y. Sakawa, Y. Sato, K. Tomita, K. Uchino, S. Matsukiyo, Y. Shoji, S. Tomita, S. Tomiya, R. Yamazaki, M. Koenig, Y. Kuramitsu, Spatial and temporal plasma evolutions of magnetic reconnection in laser produced plasmas, HIGH ENERGY DENSITY PHYSICS, 10.1016/j.hedp.2017.02.004, Vol.23, pp.15-19, 2017.06, Magnetic reconnection is experimentally investigated in laser produced plasmas. By irradiating a solid target with a high-power laser beam, a magnetic bubble is generated due to the Biermann effect. When two laser beams with finite focal spot displacements are utilized, two magnetic bubbles are generated, and the magnetic reconnection can take place. We measure the spatial and temporal plasma evolutions with optical diagnostics using framing camera. We observed the plasma jets, which are considered to be reconnection out flows. Spatial and temporal scales of the plasma jets are much larger than those of laser. The magnetic reconnection time has been estimated from the expansion velocity, which is consistent with the Sweet Parker model. (C) 2017 Elsevier B.V. All rights reserved. |
| 38. |
高出力レーザーと外部磁場を用いた磁気リコネクション実験. |
| 39. |
磁化プラズマ中を伝播する低マッハ数の無衝突衝撃波の生成実験. |
| 40. |
レーザー生成対向プラズマ中における磁気リコネクション. |
| 41. |
プラズマ衝撃波のマルチスケール構造の精密測定. |
| 42. |
高出力レーザーを用いた磁気リコネクション実験における局所プラズマ・磁場計測. |
| 43. |
Local interactions between collisionless shock and plasma: Waves, multi-scale physics, particle acceleration/heating. |
| 44. |
Shuichi Matsukiyo, Youichi Sakawa, Yasuhiro Kuramitsu, Taichi Morita, KENTARO TOMITA, Toseo Moritaka, Hideaki Takabe, Tohru Hada, Ryo Yamazaki, Taichi Ishikawa, Yuta Yamaura, Takayoshi Sano, Naohumi Ohnishi, Hitoki Yoneda, Nigel Woolsey, Robert Crowston, Gianluca Gregori, Michel Koenig, Yutong Li, Experiment of a spherical shock: Effect of the orientation of magnetic field on shock structure and particle acceleration, 2014.03. |
| 45. |
Shuichi Matsukiyo, Yasuhiro Kuramitsu, Youichi Sakawa, Taichi Morita, KENTARO TOMITA, Toseo Moritaka, Hideaki Takabe, Tohru Hada, Theoretical study on unmagnetized shocks in counter streaming plasmas, 2014.03. |
| 46. |
Shuichi Matsukiyo, Yasuhiro Kuramitsu, Youichi Sakawa, Taichi Morita, KENTARO TOMITA, Toseo Moritaka, Hideaki Takabe, Tohru Hada, Full particle-in-cell simulations on the formation of electrostatic shock in a counter streaming plasma, 2013.03. |
