UBC Theses and Dissertations
Imaging and manipulating the invariant molecular ultracold plasma state of nitric oxide Marroquín Madera, Kevin Leonardo
The core of an ellipsoidal Rydberg gas of nitric oxide undergoes spontaneous avalanche, leading to the formation of plasma. Ambipolar expansion quenches electron temperature as it radially accelerate NO⁺ ions in the core. Ballistic ions enter the wings of the ellipsoid where they engage in long-range, resonant charge transfer with frozen Rydberg molecules, equalizing the ion-Rydberg molecule relative velocity. This sequence of process gives rise to a remarkable process of self assembly, where the kinetic energy of the initially generated hot electrons and ions drives the separation of plasma volumes. These dynamics effectively store energy in a reservoir of mass transport, initiating a process that facilitates the annealing of the separating volumes into a seemingly glass like state consisting of strongly coupled ions and electrons. Experimental evidence for complete ionization is provided through short-time electron spectroscopy. Notably, the long lifetime and stability of this system, with respect to recombination and neutral dissociation, suggest that this transformation yields a resilient state of arrested relaxation, significantly deviating from thermal equilibrium. This thesis, provided direct evidence for these processes observed in the absorption spectrum of transitions to states within the selected Rydberg series, which persist as a long-lived signal even after travelling for 400 μs to reach an imaging detector. Plasma images elucidate kinetic processes that occur within the Rydberg volume, leading to the formation of a long-lived plasma that undergoes an initial density dependent bifurcation. Spectroscopic results shed light on how the initial electron density, resulting from prompt Penning ionization and varying with the chosen initial principal quantum number and Rydberg gas density, play a crucial role in determining plasma stability. This Penning-regulated ion-Rydberg equilibrium appears to be play an essential role in extending plasma lifetime, thereby enabling the detection of spectral features after significant time delays. Studies of bifurcation velocity as a function of initial Rydberg gas principal quantum number and density map patterns in plasma energy disposal and long term stability notably show that, irrespective of the initial conditions, this final bifurcated state exhibits a constant density.
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