1. Magnetic Reconnection in Plasma Plasmoid Generation and Dynamics Ravi Samtaney PSE and MCSE Divisions, KAUST

2. Motivation Solar flaresandCoronalMassEjectionsarisebecausethemagneticfieldlinesinthe Sun breakandrejoinin a differentconfiguration. • Other areas • Laser-solid interactions • Magnetic dynamo, magnetogenesis • Accretion disk flares, magnetar giant flares, gamma-ray burst and rapid TeV flares in blazars • Magnetic reconnection is an ubiquitous and important plasma physics phenomenon – solar/stellar flares, sawtooth instability, magnetosphericsubstorms, laser-solid interactions, etc. Interactionbetweenthe solar windandtheearth’smagneticfieldgivesrise to a varietyofphenomena, e.g., aurorae (source: Charles Day, Phys. Today, Oct 2001) (source: http://sohowww.nascom.nasa.gov/ )

3. Key Science Question and Essential Scientific Result • Question: Over 60 years, the plasma physics community has struggled with the question: “Why does reconnection in nature occur on much faster time scales than that predicted by theory?” • Answer: Large scale MHD simulations on Shaheen utilizing over 20 million cpu hours have shed new light on this 60 year old mystery. The reconnection layer becomes unstable for Lundquist number (S) > 104 and reconnection rate becomes essentially independent of S • Potential Impact: In 4-5 years, planned missions by NASA (MMS) and ESA (Solar Orbiter) will collect magnetic reconnection data on the earth and sun. Our theoretical/simulation studies now may impact design of, and measurements taken in these space missions Reconnection rate becomesindependent of S (top).Snapshot of a monsterplasmoid (right; entropy variable shown; simulation on16K processors on IBM Blue- Gene P, Shaheen at KAUST ) References: 1. Loureiro et al., Phy. Rev. Lett., 2007 2. Samtaney et al., Phys. Rev. Lett., 20093. Loureiro et al. submitted to PRL 2011