Magnetic reconnection present and future of in situ observations Andris Vaivads Swedish Institute of Space Physics, Uppsala Workshop, Magnetic reconnection and plasma turbulence 29 May 2007, Uppsala

Plasma - 4 th state matter near Earth space N=const in Debye sphere D / i =const

Solar wind and Earth magnetosphere ✔ In the Earth plasma sheet it is hotter than in the center of the Sun ✔ Magnetic reconnection is one of the main causes 10 thousand degrees C 300 million degrees C

Earth magnetosphere reconnection laboratory magnetotail magnetopau se Large scale current sheets (magnetotail, magnetopause) Small scale current sheets (turbulent plasma, vortices)

Movie Reconnection without magnetic field lines

Earth magnetosphere – the best in situ laboratory On all scales possible to measure ✔ Magnetic field B ✔ Electric field E ✔ Electron and ion distribution functions SCALE S Spatial scales >1000 km km 1-10 km Temporal scales > 1s 0.1 – 1 s 1-10 ms fluid ion electron

Reconnection at magnetopauses of other planets Jupiter Mercury ✔ Flux Transfer Events indicate nonsteady reconnection at the magnetopause ✔ Easy to identify as bipolar Bn signature [Russell 2000, ASR]

Reconnection in tokamaks Batchelor 2005 Courtesy Hyeon K. Park

JW=738, age 10Myr one of the most powerfull X-ray flares ever J Substorms J Solar flare J Courtesy Y. Khotyaintsev Reconnection onset

Accretion disks [Tajima, 1995] ✔ Matter falling in gets ionized ✔ Part of energy and momentum it looses forming magnetic field (dynamo) ✔ Magnetic field through reconnection can form flares (and jets?)

Microscale MMS separation 1R E [km] ,000 Cluster separation Multiscales in Earth magnetosphere Cross-Scale separation Debye Magnetopause e- scaleH+ scaleMHD scale Magnetotail Debyee- scaleH+ scaleMHD scale Reconnection double layers solitary, plasma, ion acoust waves Current sheets LHDI e- energiz. diffus reg. KAW whistlers separatrix ion energiz. ion diffus reg. Alfvén waves magnetic islands externa l driving reconnection jets Turbulence Dissipation rangeInertial range Alfvén turbulence Lower hybrid turbulence Alfvén vortices KH turbulenceplasma wave / ion acoustic turbulence electron energization ion energization

The art of compromise spatial resolution temoral resolution particle energy particle species Resources + art to build art to manage work private relatives 24h

Cluster (ESA) 3D plasma measurements

[Retinò et al., 2007, Nat. Phys.] [Omidi et al., 2005, JGR] ✔ Narrow current sheets in turbulent plasma [Retinò et al., 2007, Nat. Phys.] B ✔ current sheet seen by 4 spacecraft Reconnecting current sheets in turbulent plasma ✔ particle distr. function cannot be resolved

cavity [Khotyaintsev et al., 2006, PRL] ✔ Separatrix region is narrow a few c/  pi ✔ strong J II ✔ density cavity ✔ strong En, potential jump Reconnection separatrix region

Extended reconnection line [Phan et al., 2006]

THEMIS (NASA) Substorms – distinguish two existing models Launch Remind me to show movie!!!

BepiColombo (ESA/JAXA) Mercury Planetary Orbiter (MPO) Mercury Magnetospheric Orbiter (MMO) Launch 2013 (arrival 2019)

Magnetospheric Multiscale (MMS) mission NASA Solar-Terrestrial Probe mission launch 2013 SMART- Solving Magnetospheric Acceleration, Reconnection and Turbulence

MMS (NASA) Magnetic reconnection (shocks, turbulence) Resolving electron scales Launch 2013 e- time res s i+ time resol. 0.2 s (Cluster 4s)

ESA Cosmic Vision What are the conditions for life and planetary formation? How does the Solar System work? What are the fundamental laws of the Universe? How did the Universe begin and what is it made of? IHP Sample return JME Cross-Scale Mars Europa Lisa GWE XEUS Large aperture X-ray All sky CMB

Cross-Scale Cluster 3 scales simultaneously - fluid (MHD) - ion - electrons 1 scale at a time during the mission has covered scales from slightly below ion scale to fluid scale

Reconnection – multiple scales [Daughton et al., 2004] JyJy T perp /T ||  potential jump Lower-hybrid drift waves Anisotropic heating of electrons

Summary ✔ Earth – best in situ reconnection laboratory ✔ Compromise: temporal/spatial/energy ✔ Cluster: 3D plasma measurements ✔ Global scale: Wind, Geotail ✔ Exploration: Bepi Colombo ✔ Next level 3D building: MMS ✔ Next level 3D hoping: Cross-Scale