Three-dimensional imaging of the ultracold plasma formed in a supersonic molecular beam

Journal Article · Mon Jun 29 00:00:00 EDT 2015 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.4923121· OSTI ID:22490701

Schulz-Weiling, Markus; Grant, Edward ^[1]

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1. Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1 Canada (Canada)

Double-resonant excitation of nitric oxide in a seeded supersonic molecular beam forms a state-selected Rydberg gas that evolves to form an ultracold plasma. This plasma travels with the propagation of the molecular beam in z over a variable distance as great as 600 mm to strike an imaging detector, which records the charge distribution in the dimensions, x and y. The ω{sub 1} + ω{sub 2} laser crossed molecular beam excitation geometry convolutes the axial Gaussian distribution of NO in the molecular beam with the Gaussian intensity distribution of the perpendicularly aligned laser beam to create an ellipsoidal volume of Rydberg gas. Detected images describe the evolution of this initial density as a function of selected Rydberg gas initial principal quantum number, n{sub 0}, ω{sub 1} laser pulse energy (linearly related to Rydberg gas density, ρ{sub 0}) and flight time. Low-density Rydberg gases of lower principal quantum number produce uniformly expanding, ellipsoidal charge-density distributions. Increase either of n{sub 0} or ρ{sub 0} breaks the ellipsoidal symmetry of plasma expansion. The volume bifurcates to form repelling plasma volumes. The velocity of separation depends on n{sub 0} and ρ{sub 0} in a way that scales uniformly with ρ{sub e}, the density of electrons formed in the core of the Rydberg gas by prompt Penning ionization. Conditions under which this electron gas drives expansion in the long axis dimension of the ellipsoid favours the formation of counter-propagating shock waves.

• OSTI ID: 22490701
• Journal Information: AIP Conference Proceedings, Vol. 1668, Issue 1; Conference: 11. international workshop on non-neutral plasmas, Takamatsu (Japan), 1-4 Dec 2014; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CHARGE DENSITY
CHARGE DISTRIBUTION
DENSITY
ELECTRON GAS
ELECTRONS
EXCITATION
GASES
GAUSS FUNCTION
IONIZATION
LASERS
MOLECULAR BEAMS
NITRIC OXIDE
PLASMA
PLASMA EXPANSION
SHOCK WAVES
THREE-DIMENSIONAL CALCULATIONS
THREE-DIMENSIONAL LATTICES
VELOCITY