研究・研究者
研究会・セミナー
| 演 題 | 「Properties of a Novel Ultra-cold Quantum Degenerate Plasma」 |
|---|---|
| 日 時 | 2014年05月15日(木) 16:00 より 17:00 まで |
| 講演者 | Klaus Müller-Dethlefs (The University of Manchester, Professor) |
| 場 所 | 分子科学研究所 研究棟2階 201セミナー室 |
| 概 要 |
We are producing an ultra-cold Rydberg plasma by laser threshold ionization of NO molecules in the high-density, high-collision rate expansion region of a pulsed supersonic free jet expansion (10% NO in Ne) close to the nozzle. The plasma produced shows little expansion and has an extremely long lifetime. It is probed experimentally after several hundred μs when impinging on a conducting metal plate with a small aperture. By measuring what has been transmitted through the aperture the plasma cloud size and its density can be determined. The plasma cloud is characterised by a very small high-density core of the order of a mm surrounded by a lower density region. The plasma cloud shows the compressibility of a “sponge like” ultra-soft solid or liquid.
For the plasma densities of < 1016 cm–3 reached in our experiments the electrons should become quantum degenerate. The condition for quantum degeneracy is that the electron de Broglie wavelength must be larger than the mean distance between particles, or the Wigner-Seitz radius. According to textbook plasma physics the degeneracy condition for the electrons in an ultra-cold ion-electron plasma is fulfilled for an initial electron temperature of 0.1K and a density above 1013 cm–3.
An intriguing observation is that the NO dimer and trimer also form a plasma which shows a striking difference in its compression behavior compared to the NO monomer plasma. A possible explanation is the formation of a mixed monomer/cluster ion crystal embedded in the degenerate electron fluid.
Presently, two applications for this novel plasma could be of interest: |
| お問合せ先 | 大島康裕・大森賢治 |
