Departmental Oral Examination (Thesis Title: “Ultracold Molecular Plasma”)

Speaker: 
MARKUS SCHULZ-WEILING
Event Date and Time: 
Tue, 2017-04-18 09:15 - 11:15
Location: 
Henn 318
Local Contact: 
Physics and Astronomy, UBC
Intended Audience: 
Public

Abstract:
The conditions afforded by a skimmed free-jet expansion intersected by two laser pulses, driving resonant transitions in nitric oxide, determine the phase-space volume of a molecular Rydberg ensemble. Spontaneous avalanche to plasma within this system leads to the development of two macroscopic domains. These domains are clearly distinguished by their polarizability as well as their locality within the plasma. The first domain appears at the system core, is polarized by fields exceeding 500 mV/cm and displays an ambipolar expansion character suggestive of initial electron temperatures exceeding ∼150 Kelvin. The second domain travels with the velocity of the supersonic beam and is robust to the application of several hundred V/cm pulses. It is further distinguished through the apparent arrest of relaxation channels, annealing the domain over a millisecond or more in a state far from thermal equilibrium. Both domains are linked via the spontaneous breaking of ellipsoidal symmetry to form bifurcating arrested volumes. I discuss our observations and speculate on the nature of the arrested domain as well as its mechanism of formation.

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