Plasma Physics Seminar ( Phys 769)

Jan Egedal, MIT

Magnetic Reconnection in Plasmas; a Celestial Phenomenon in the Laboratory

Magnetic reconnection in a low collisional regime is studied on the Versatile Toroidal Facility (VTF) at MIT. The detailed evolution of the profiles of plasma density, current density, and electrostatic potential at the onset of driven reconnection is measured experimentally. The VTF device facilitates experiments with two distinct sets of boundary conditions: an "open" configuration for which the field lines intersect the vacuum vessel walls, and a "closed" configuration for which the magnetic field lines form closed loops inside the device. For the open configuration our studies reveal a new mechanism - particle trapping - responsible for fast reconnection. This mechanism is found to be consistent with unique spacecraft observations deep in the Earth's magnetotail. In the talk I will discuss our experimental observations of magnetic reconnection in the open configuration, provide a theoretical explanation, and apply the theory to the spacecraft observations. I will also discuss preliminary results from the closed configuration.