Helicities in Geophysics, Astrophysics, and Beyond

List of contributors vii

Preface ix

Part I Helicity Essentials: Basic and Fundamental Concepts 1

1 Introduction to Field Line Helicity 3
Anthony R. Yeates and Mitchell A. Berger

2 Magnetic Winding: Theory and Applications 17
David MacTaggart

3 Transport in Helical Fluid Turbulence 25
Nobumitsu Yokoi

Part II Helicity Manifestations in Nature and Their Observations 51

4 Observations of Magnetic Helicity Proxies in the Solar Photosphere: Helicity With Solar Cycles 53
Hongqi Zhang, Shangbin Yang, Haiqing Xu, Xiao Yang, Jie Chen, and Jihong Liu

5 Chirality of Solar Filaments and the Supporting Magnetic Field 75
Peng-Fei Chen

6 Solar Flares and Magnetic Helicity 83
Shin Toriumi and Sung-Hong Park

7 Magnetic Helicity Measurements in the Solar Wind 105
Yasuhito Narita

8 Magnetic Helicity in Rotating Neutron Stars 117
Maxim Dvornikov

9 Writhing From Biophysics to Solar Physics and Back 133
Christopher Prior and Arron N. Bale

10 Kinetic Helicity in the Earth's Atmosphere 149
Otto Chkhetiani and Michael Kurgansky

Part III Theoretical and Numerical Helicity Modeling 167

11 Effects of P-Noninvariance, Particles, and Dynamos 169
Victor B. Semikoz and Dmitry D. Sokoloff

12 Stability of Plasmas Through Magnetic Helicity 179
Simon Candelaresi and Fabio Del Sordo

13 Helicity-Conserving Relaxation in Unstable and Merging Twisted Magnetic Flux Ropes 189
Philippa K. Browning, Mykola Gordovskyy, and Alan W. Hood

14 Emergence of Magnetic Structure in Supersonic Isothermal Magnetohydrodynamic Turbulence 203
Jean-Mathieu Teissier and Wolf-Christian Müller

15 Nonlinear Mean-Field Dynamos With Magnetic Helicity Transport and Solar Activity: Sunspot Number and Tilt 217
Nathan Kleeorin, Kirill Kuzanyan, Igor Rogachevskii, and Nikolai Safiullin

16 The Spatial Segregation of Kinetic Helicity in Geodynamo Simulations 241
Avishek Ranjan and Peter Davidson

Index 259