Dr Istvan Ballai
School of Mathematics and Statistics
Senior Lecturer
+44 114 222 3833
Full contact details
School of Mathematics and Statistics
H9
Hicks Building
Hounsfield Road
Sheffield
S3 7RH
 Research interests

Dr. Istvan Ballai's main research interest is in linear and nonlinear MHD waves occurring in solar and interplanetary plasmas.
Waves can carry energy and momentum; when transferred to inhomogeneous plasmas they can heat or accelerate the plasma therefore MHD waves may play an important role in explaining the observed high temperatures in the solar corona. Waves can transport information about the environment in which they propagate, so they serve as a perfect tool for plasma diagnostics.
We use local and global coronal waves to find average values for magnetic field and transport coefficients in the solar corona. When the temperature of the plasma is not high enough to ensure a full ionisation, the plasma becomes partially ionised with particles of different species colliding and modifying each other momentum and energy.
Dr Istvan Ballai's reserch interest also covers dynamical aspects in such plasmas, including waves and instabilities, nonequilibrium effects, etc.
 Publications

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Journal articles
 Parametric resonance of Alfvén waves driven by ionizationrecombination waves in the weakly ionized solar atmosphere. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 382(2272).
 Slow body magnetohydrodynamic waves in solar photospheric flux tubes with density inhomogeneity. Monthly Notices of the Royal Astronomical Society, 529(1), 748760.
 Magnetohydrodynamic Poynting Flux Vortices in the Solar Atmosphere and Their Role in Concentrating Energy. The Astrophysical Journal, 963(1), 1010.
 Phase Mixing of Propagating Alfvén Waves in a Singlefluid Partially Ionized Solar Plasma. The Astrophysical Journal, 958(1), 8181.
 The Temporal and Spatial Evolution of Magnetohydrodynamic Wave Modes in Sunspots. The Astrophysical Journal, 954(1), 3030.
 Atmospheric waves disturbances from the solar terminator according to the VLF radio stations data. Advances in Space Research.
 Novel approach to forecasting photospheric emergence of active regions. The Astrophysical Journal Letters, 948(2).
 PREFACE: Recent progress in the physics of the Sun and heliosphere. Advances in Space Research.
 Comparison of Exact and Approximate MHD Slow Body Mode Solutions in Photospheric Waveguides. The Astrophysical Journal, 938(1), 3232.
 Smallscale solar jet formation and their associated waves and instabilities. Advances in Space Research.
 MHD wave modes of solar magnetic flux tubes with the realistic crosssection.
 New Approach for Analyzing Dynamical Processes on the Surface of Photospheric Vortex Tubes. The Astrophysical Journal, 928(1), 33.
 Magnetohydrodynamic Wave Mode Identification in Circular and Elliptical Sunspot Umbrae: Evidence for Highorder Modes. The Astrophysical Journal, 927(2), 201201.
 The importance of horizontal Poynting flux in the solar photosphere. The Astrophysical Journal, 927(2).
 Waves in weakly ionized solar plasmas. Monthly Notices of the Royal Astronomical Society, 511(4), 52745286.
 Approbation of wave dispersion analysis using multispacecraft methods. Bulletin of Taras Shevchenko National University of Kyiv. Astronomy(66), 2025.
 Critical science plan for the Daniel K. Inouye solar telescope (DKIST). Solar Physics, 296(4). View this article in WRRO
 Proper orthogonal and dynamic mode decomposition of sunspot data. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 379(2190). View this article in WRRO
 Slow magnetoacoustic waves in gravitationally stratified twofluid plasmas in strongly ionized limit. Monthly Notices of the Royal Astronomical Society, 501(2), 19401950.
 Generation of lowfrequency kinetic waves at the footpoints of preflare coronal loops. Solar Physics, 295(12). View this article in WRRO
 Diagnostics of plasma ionisation using torsional Alfén waves. Astronomy & Astrophysics, 635. View this article in WRRO
 Magnetic RayleighTaylor instability at a contact discontinuity with an oblique magnetic field. Astronomy and Astrophysics. View this article in WRRO
 Linear Waves in Partially Ionized Plasmas in Ionization Nonequilibrium. Frontiers in Astronomy and Space Sciences, 6. View this article in WRRO
 Propagation of leaky surface waves on contact magnetohydrodynamic discontinuities in incompressible plasmas. Physics of Plasmas, 25(12). View this article in WRRO
 Dispersive shock waves in partially ionised plasmas. Advances in Space Research. View this article in WRRO
 Propagation of Leaky MHD Waves at Discontinuities with Tilted Magnetic Field. Solar Physics, 293. View this article in WRRO
 RayleighTaylor instabilities with sheared magnetic fields in partially ionised plasmas. Astronomy & Astrophysics, 609, A23A23. View this article in WRRO
 Dissipative instabilities in a partially ionised prominence plasma slab. Astronomy & Astrophysics, 610, A56A56. View this article in WRRO
 Dissipative instability in a partially ionised prominence plasma slab. Astronomy & Astrophysics. View this article in WRRO
 Statistical study of spatiotemporal distribution of precursor solar flares associated with major flares. Monthly Notices of the Royal Astronomical Society, 459(4), 35323539. View this article in WRRO
 Dissipative instability in partially ionised prominence plasmas. Astronomy & Astrophysics, 577, A82A82. View this article in WRRO
 The P
1 /P2 period ratio for kink oscillations of an asymmetrical coronal loop. Astronomische Nachrichten, 334(9), 948951.  Magnetoacoustic surface gravity waves at a spherical interface. ASTRON ASTROPHYS, 527.
 The dynamical solar atmosphere. Journal of Physics: Conference Series, 218(1).
 Mean shear flows generated by nonlinear resonant Alfveacuten waves. PHYS PLASMAS, 16(7). View this article in WRRO
 Nonlinear resonant absorption of fast magnetoacoustic waves in strongly anisotropic and dispersive plasmas. PHYS PLASMAS, 16(4). View this article in WRRO
 On the validity of nonlinear Alfven resonance in space plasmas. ASTRON ASTROPHYS, 494(1), 317327. View this article in WRRO
 The problem of phase mixed shear Alfven waves in the solar corona revisited. ASTRON NACHR, 329(8), 780785. View this article in WRRO
 Forced oscillations of coronal loops driven by EIT waves. ASTRON ASTROPHYS, 488(3), 11251132. View this article in WRRO
 Nonlinear theory of resonant slow waves in anisotropic and dispersive plasmas. PHYS PLASMAS, 15(8). View this article in WRRO
 MHD waves at a spherical interface modelling EIT waves. ASTRON NACHR, 328(8), 769772.
 Dispersive shock waves in the solar wind. ASTRON NACHR, 328(8), 734737.
 Untitled. ASTRON NACHR, 328(8), 725725.
 Heating of the solar and stellar coronae: a review. ASTRON NACHR, 328(8), 726733.
 Thermosolutal stability of a twocomponent rotating plasma with finite Larmor radius. PROC ROM ACAD SER A, 8(2), 111120.
 Thermally damped linear compressional waves in a 2D solar coronal model. Proceedings of the International Astronomical Union, 3(S247), 320323. View this article in WRRO
 MHD waves at a spherical interface modelling coronal global EIT waves. Proceedings of the International Astronomical Union, 3(S247), 251254.
 Coronal global EIT waves as tools for multiple diagnostics. Proceedings of the International Astronomical Union, 3(S247), 243250. View this article in WRRO
 Sampling the coronal magnetic field. AIP Conference Proceedings, 934, 4453.
 The damping of slow magnetoacustic waves in coronal loops. J OPTOELECTRON ADV M, 8(4), 15621564.
 Magnetohydrodynamic modes in a periodic magnetic steady state medium. ASTRON ASTROPHYS, 449(3), 11931202.
 Slow magnetohydrodynamic waves in stratified and viscous plasmas. PHYS PLASMAS, 13(4).
 Untitled. PHILOS T ROY SOC A, 364(1839), 471472.
 Diagnostics of local and global coronal magnetic field using global coronal waves. Proceedings of the International Astronomical Union, 2(233), 132133.
 Propagating magnetohydrodynamics waves in coronal loops. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 364(1839), 461472.
 On the nature of coronal EIT waves. ASTROPHYS J, 633(2), L145L148.
 The sound of the Sun. ASTRON GEOPHYS, 46(4), 2730.
 Seismology of the sun: From the inner core to the corona. Observatory, 125(1187), 224227.
 The Sun: for academics, students and idiots. Astronomy and Geophysics, 45(4), 4.444.45.
 The effect of anisotropy on the propagation of linear compressional waves in magnetic flux tubes: Applications to astrophysical plasmas. ASTRON ASTROPHYS, 415(2), 691703.
 Damping of compressional waves in coronal prominences. European Space Agency, (Special Publication) ESA SP(547), 211214.
 Damping of coronal EIT waves as a tool for plasma diagnostics. European Space Agency, (Special Publication) ESA SP(547), 433440.
 On dissipative effects in solar prominences. ASTRON ASTROPHYS, 410(2), L17L19.
 Linear and nonlinear MHD wave propagation in steadystate magnetic cylinders. SOL PHYS, 217(2), 199223.
 Solitary waves in a Hall solar wind plasma. ASTRON ASTROPHYS, 404(2), 701707.
 Extended LeibovichRoberts equation in rarefied plasmas. PHYS PLASMAS, 9(10), 42804284.
 Ducted compressional waves in the magnetosphere in the doublepolytropic approximation. ANN GEOPHYSGERMANY, 20(10), 15531558.
 Linear and nonlinear wave propagation in rarefied plasmas. PHYS PLASMAS, 9(6), 25932603.
 Dynamics of nonlinear resonant slow MHD waves in twisted flux tubes. NONLINEAR PROC GEOPH, 9(2), 7986.
 Nonlinear theory of resonant slow MHD waves in twisted magnetic flux tubes. J PLASMA PHYS, 67, 7997. View this article in WRRO
 Nonlinear resonant absorption of fast magnetoacoustic waves due to coupling into slow continue in the solar atmosphere. ASTRON ASTROPHYS, 368(2), 662675.
 View this article in WRRO Nonlinear theory of nonaxisymmetric resonant slow waves in straight magnetic flux tubes. J PLASMA PHYS, 64, 579599.
 View this article in WRRO Linear and nonlinear resonant interaction of sound waves in dissipative layers. J PLASMA PHYS, 64, 235247.
 Resonant absorption of nonlinear slow MHD waves in isotropic steady plasmas  II. Application: Resonant acoustic waves. SOL PHYS, 186(12), 6797.
 Resonant absorption of nonlinear slow MHD waves in isotropic steady plasmas  I. Theory. SOL PHYS, 180(12), 6579.
 Interaction of sound waves with slow dissipative layers in anisotropic plasmas in the approximation of weak nonlinearity. PHYS PLASMAS, 5(6), 22642273.
 Nonlinear theory of slow dissipative layers in anisotropic plasmas. PHYS PLASMAS, 5(1), 252260.
 Turbulent dipolarization regions in the Earth’s magnetotail: ion fluxes and magnetic field changes. Frontiers in Astronomy and Space Sciences, 10, 1226200.
 Magnetic Energy Powers the Corona: How We Can Understand its 3D Storage & Release. Vol. 55, Issue 3 (Heliophysics 2024 Decadal Whitepapers), 55(3).
 Generation of Localised Vertical Streams in Unstable Stratified Atmosphere. Fluids, 6(12), 454454.
 Statistical relationship between the succeeding solar flares detected by the RHESSI satellite. MNRAS, 441, 11571165. View this article in WRRO
 Threedimensional numerical simulation of magnetohydrodynamicgravity waves and vortices in the solar atmosphere. View this article in WRRO
 Sausage Mode Propagation in a Thick Magnetic Flux Tube. 2013SoPh..tmp..229P. View this article in WRRO
 Transverse kink oscillations of expanding coronal loops. View this article in WRRO
 The effect of the environment on the P1/P2 period ratio for kink oscillations of coronal loops. View this article in WRRO
 TRACE Observations of Driven Loop Oscillations.
 Nonlinear effects in resonant layers in solar and space plasmas.
 Resonant Absorption of Fast Magnetoacoustic Waves due to Coupling into the Slow and Alfven Continua in the Solar Atmosphere. Solar Physics 06/2010.
 The effect of longitudinal flow on resonantly damped kink oscillations.
 Timedependent properties of sunspot groups. I. Lifetime and asymmetric evolution. Astronomy and Astrophysics.
Conference proceedings papers
 Waveparticle interactions in the Earth magnetotail during dipolarization. EGU General Assembly 2023. Vienna, Austria, 23 April 2023  23 April 2023. View this article in WRRO
 View this article in WRRO Sheffield University Nova Rocket Innovative Design Engineering (SUNRIDE). 24th ESA Symposium on European Rocket and Balloon Programmes and Related Research Proceedings (pp 122127). Noordwijk, The Netherlands, 16 June 2019  20 June 2019.
 Global coronal seismology. SOLAR PHYSICS, Vol. 246(1) (pp 177185)
 Thermally damped waves in the solar corona. FLOWS, BOUNDARIES, INTERACTIONS, Vol. 934 (pp 6470)
 MHD waves in stratified and dissipative plasmas. Fifty Years of Romanian Astrophysics, Vol. 895 (pp 141146)
 Nonlinear waves in solar plasmas  a review. First International Workshop and Summer School on Plasma Physics, Vol. 44 (pp 2029)
 Wave damping in hall plasmas  Application to the solar wind. SOLMAG 2002: PROCEEDINGS OF THE MAGNETIC COUPLING OF THE SOLAR ATMOSPHERE EUROCONFERENCE AND IAU COLLOQUIUM 188, Vol. 505 (pp 345348)
 Linear and nonlinear waves in dilute plasmas. WAVES IN DUSTY, SOLAR, AND SPACE PLASMAS, Vol. 537 (pp 152159)
 Absorption of fast magnetosonic waves in the solar atmosphere in the limit of weak nonlinearity. WAVES IN DUSTY, SOLAR, AND SPACE PLASMAS, Vol. 537 (pp 144151)
 Strongly nonlinear resonant MHD waves in the steady solar magnetic canopy. 9TH EUROPEAN MEETING ON SOLAR PHYSICS: MAGNETIC FIELDS AND SOLAR PROCESSES, VOLS 1 AND 2, Vol. 448 (pp 263267)
 Nonlinear resonant MHD waves in the atmosphere of the sun. 8TH SOHO WORKSHOP: PLASMA DYNAMICS AND DIAGNOSTICS IN THE SOLAR TRANSITION REGION AND CORONA, PROCEEDINGS, Vol. 446 (pp 155160)
Preprints
 Sausage, kink, and fluting MHD wave modes identified in solar magnetic pores by Solar Orbiter/PHI, arXiv.
 Phase mixing of propagating Alfv{é}n waves in a singlefluid partially ionized solar plasma.
 Atmospheric waves disturbances from the solar terminator according to the VLF radio stations data, arXiv.
 The temporal and spatial evolution of MHD wave modes in sunspots.
 Comparison of exact and approximate MHD slow body mode solutions in photospheric waveguides, arXiv.
 Smallscale solar jet formation and their associated waves and instabilities, arXiv.
 The importance of horizontal Poynting flux in the solar photosphere, arXiv.
 New approach for analysing dynamical processes on the surface of photospheric vortex tubes, arXiv.
 Waves in weakly ionised solar plasmas, arXiv.
 Magnetohydrodynamic wave mode identification in circular and elliptical sunspot umbrae: evidence for high order modes, arXiv.
 Timedependent properties of sunspot groups  I. Lifetime and asymmetric evolution, arXiv.
 Slow magnetoacoustic waves in gravitationally stratified twofluid plasmas in strongly ionised limit, arXiv.
 Proper Orthogonal and Dynamic Mode Decomposition of Sunspot Data, arXiv.
 Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST), arXiv.
 Diagnostics of plasma ionisation using torsional Alfén waves, arXiv.
 Magnetic RayleighTaylor Instability at a Contact Discontinuity With Oblique Magnetic Field, arXiv.
 Dispersive shock waves in partially ionised plasmas, arXiv.
 Propagation of Leaky MHD Waves at Discontinuities with Tilted Magnetic Field, arXiv.
 Dissipative instabilities in a partially ionised prominence plasma slab: II. The effect of compressibility, arXiv.
 Dissipative instability in a partially ionised prominence slab, arXiv.
 Statistical study of spatiotemporal distribution of precursor solar flares associated with major flares, arXiv.
 Dissipative instability in partially ionised prominence plasmas, arXiv.
 Statistical relationship between the succeeding solar flares detected by the RHESSI satellite, arXiv.
 Sausage Mode Propagation in a Thick Magnetic Flux Tube, arXiv.
 Threedimensional numerical simulation of magnetohydrodynamicgravity waves and vortices in the solar atmosphere, arXiv.
 Transverse kink oscillations of expanding coronal loops, arXiv.
 The effect of the environment on the P1/P2 period ratio for kink oscillations of coronal loops, arXiv.
 TRACE Observations of Driven Loop Oscillations, arXiv.
 Nonlinear effects in resonant layers in solar and space plasmas, arXiv.
 Resonant Absorption of Fast Magnetoacoustic Waves due to Coupling into the Slow and Alfven Continua in the Solar Atmosphere, arXiv.
 The effect of longitudinal flow on resonantly damped kink oscillations, arXiv.
 Mean shear flows generated by nonlinear resonant Alfven waves, arXiv.
 Nonlinear resonant absorption of fast magnetoacoustic waves in strongly anisotropic and dispersive plasmas, arXiv.
 On the validity of nonlinear Alfven resonance in space plasmas, arXiv.
 Nonlinear theory of resonant slow waves in anisotropic and dispersive plasmas, arXiv.
 Forced oscillations of coronal loops driven by EIT waves, arXiv.
 Global coronal seismology, arXiv.
 Research group
 Grants

Past grants, as Principal Investigator
Instabilities in partially ionized prominence plasmas Leverhulme Damping of Forced Oscillations in Coronal Loops RS Conference Attendance RS Global Coronal Seismology Using SOHO/EIT Observations Nuffield Past grants, as Coinvestigator
Application to STFC for Consolidated Grant Support for the Solar Physics and Space Plasma Research Centre (SP2RC) STFC Consolidated Grant Support for the Solar Physics and Space Plasma Research Centre (SP2RC) STFC Heating and MagnetoSeismology of the Solar Atmosphere STFC
 Teaching interests

 Differential and difference equations
 Complex Analysis
 Numerical methods