1. Meeting 5 April 5, 2006 Comparative Aspects of Particle Acceleration and Reconnection

2. Welcome Purpose: –To facilitate interaction among colleagues in space science in the New England Area (UNH, CfA, BU, MIT, Hanscom/AFRL, Haystack, Dartmouth, Heliophysics Inc, ATK) –To leverage these interactions for initiating new, cross-disciplinary and far-reaching projects Meetings: –Monthly meetings (first wed each month) –Are the meetings getting too long?

3. Discussion/Interdisciplinarity Topic- Potential overlap between disciplines Themes in common between disciplines Where we are in the research Problems that will need to be solved to make further progress Potential for resolution

4. MIT May 10th, next Meeting –Topic suggestions …

5. (from ongoing discussion) Recent meetings highlighted comparative approaches to space science. Continuing this theme, energetic particle acceleration at shocks and associated with magnetic reconnection. Reconnection and particlea cceleration are fundamental physical processes involving an inherent connection between microphysics (wave-particle interactions andturbulence) and the macrophysical evolution of the plasma itself. By comparing the effects of shocks and reconnection in different space environments, –we hope to broaden, generalize, specify our understanding

6. What is the right question (reconnection) Is the Axford conjecture correct? –Micro-physics vs. a driven system 3-Dimensionality is critical Examples: –Transpolar potential example (substorm) –Solar problem? CMEs, plasmoids in the downtail –Lifetime of the flare ribbons, relaxation process –Sequence of events in substorms (Cluster) –Find the method to distinguish paradigms (e.g., test the Axford conjecture) Intermittency of Reconnection

7. Summary (1 of 2) Magnetic Reconnection plays a critical role in the evolution of large- scale magnetic topologies, the rapid heating of plasmas and possibly the acceleration of high energy particles. The microphysics of reconnection is certainly complex and remains an area of active research. Despite this complexity, the "Axford Conjecture" puts forth a relatively simple condition that reconnection takes place at an average rate determined by external boundary conditions. In other words, the microphysics may adjust to the macrophysical constraints imposed on the system. If so, the quantitative effects of reconnection may be relatively straightforward to predict in diverse astrophysical environments. Comparing the effects of reconnection in disparate plasmas may provides a means to test the Axford Conjecture. A good example is found in the plasmoids released in the magnetotail during substorms. Is this phenomenon a direct parallel to coronal mass ejections, in which magnetic buoyancy plays the central in the release of a disturbance (plasmoid or CME)? If so, this comparative example would provide support for the Axford conjecture.

8. Summary (2 of 2) Magnetic reconnection also appears to be intermittent. Is this a result of the external boundary conditions? In the case of CMEs, when does the system become unstable, and what makes it erupt. This same question may be asked of plasmoids in the magnetotail. Intermittency also appears in the laboratory experiments that achieve magnetic reconnection. At first glance, intermittency seems to be a result of the creation of thin current sheets, suggesting the release of energy of very small spatial and temporal scales. In this respect, it may be natural that the dissipation of thin current sheets channels significant quantities of energy into a minority of plasma particles that participate in the dissipation of thin current sheet.

9. Schedule: 11:30Opening Remarks (Smith) 11:40Mihir Desai / Chuck Smith “Composition Signatures in ESP and SEP Acceleration” 12:05John Kohl / Alexander Panasyuk “Suprathermal Tails in Coronal Proton Velocity Distributions” 12:30Lunch (provided by UNH/SSC) 13:15Kelly Korreck “Seed Population Heating with Respect to CMEs” 13:40Marty Lee “Particle Acceleration in CMEs” 14:05Peter Foukal “Detecting Reconnection Electric Fields Using Stark Effect” 14:30Coffee Break 14:45Terry Forbes “Particle Acceleration in Flares” 15:10Ben Chandran “Particle Acceleration by MHD Turbulence in Solar Flares” 15:35Nathan Schwadron “Particle Acceleration in Turbulent Media, Structured Shocks” 16:00Edward Cliver “Electrons and Protons in SEP Events”