Abstract
We have measured the drift velocity, v, of negative ions in He II at a temperature of 0.34 K and a pressure of 25 bar¶ for electric fields, E , in the range 5 x 10 3 < E < 6 x 10 6 V m -1 . For v <70 m s -1 , the results are in good agreement with the predictions of the roton pair-emission theory of Bowley & Sheard. Even better agreement is obtained by extending the theory to take explicit account of departures from parabolicity of the real dispersion curve at large momenta, variations in the pole strength of high momentum excitations, and the slight increase in the average momentum of excitations emitted at large values of v. For v> 70 m s -1 , however, experiment and theory are in clear disagreement: by v = 80 m s -1 , the measured drag on the ion has become about 100 % larger than the theoretical prediction. We tentatively attribute this discrepancy to the onset at v« 70 m s -1 of a new and, so far, unidentified dissipation mechanism.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.