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Relaxation of cold plasmas and threshold lowering effect
1TRG, 5916 Old Greenway Drive, Glen Allen, Virginia 23059, USA.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 3, 2001
Summary
Low temperature plasmas exhibit an energy shift due to ion fields, increasing electron kinetic energy. This impacts recombination rates and plasma relaxation, revealing a new adiabatic motional recombination mode.
Area of Science:
- Atomic and Molecular Physics
- Plasma Physics
- Condensed Matter Physics
Background:
- Low temperature plasmas are generated via photoionization of cold trapped atoms.
- Overlapping ion fields cause a threshold energy shift, affecting electron kinetic energy.
Purpose of the Study:
- To investigate the energy shift in cold plasmas and its impact on plasma properties.
- To determine the universal constant C(P) and minimum electron temperature.
- To analyze three-body recombination probabilities and plasma relaxation mechanisms.
Main Methods:
- Utilizing a Debye shielded, fluctuating lattice model for self-consistent determination of C(P).
- Analyzing the relationship between plasma density and minimum electron temperature.
- Investigating the effects of energy shift on Rydberg states and recombination rates.
Main Results:
- The effective kinetic energy of free electrons increases by delta(P)=2C(P)/a.
- The minimum electron temperature is determined by plasma density: T(e) approximately 7/a.
- A new mode of adiabatic motional recombination dominates relaxation in freely expanding cold plasmas.
Conclusions:
- Wigner crystallization is not possible in these plasmas without external fields.
- The energy shift imposes a cutoff on high Rydberg state contributions to recombination.
- Adiabatic motional recombination is a key process in cold plasma relaxation.