Study of Exotic Ions in Superfluid Helium-4 Using a Carbon Nanotube Source

W Wei,H J Maris,Z-L Xie,G M Seidel,Y Yang

doi:10.1088/1742-6596/568/1/012011

W Wei, H J Maris + Show 3 more

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https://doi.org/10.1088/1742-6596/568/1/012011

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Abstract

We have extended our measurements of the properties of exotic negatively-charged ions in superfluid helium-4. We measured the ion mobility using the time-of-of-flight method at temperatures in the range between 1.03 and 1.16 K. Ions were generated by an electrical discharge produced by applying a voltage to sharp tips in the helium vapor above the liquid surface. Previous studies by Ihas and Sanders, Eden and McClintock, and by our group used tungsten tips and were able to detect at least twelve exotic ions in addition to the normal electron bubble. In the present work we have experimented with tips each consisting of a stainless steel wire coated with carbon nanotubes. We have found that with these tips the strength of the exotic ion signal is substantially increased making it possible to detect several ions which previously could not be seen. The present data combined with the results of the previous studies indicate that there are at least eighteen exotic ions with different mobility.

Highlights

Studies of ion mobility in superfluid helium-4 have revealed the existence of a number of negatively charged objects in addition to the well-studied normal electron bubble (NEB)
Ions were drawn from the vapor into the liquid. These experiments demonstrated the existence of at least 13 so-called “exotic ions” with mobility lying between the mobility of the fast ion and the NEB
Summary As emphasized in the introduction, there is no accepted theory of the physical nature of the exotic ions

Summary

Introduction

Introduction Studies of ion mobility in superfluid helium-4 have revealed the existence of a number of negatively charged objects in addition to the well-studied normal electron bubble (NEB). Ihas and Sanders [2] and Eden and McClintock [3] generated ions by applying a voltage to a sharp tip in the vapor above the liquid to produce an electrical discharge. It has recently been found that as well as the ions with 13 different and discrete values of mobility, there is a large component in the measured signal which comes from ions which have appear to have a continuous distribution of mobility [4].

Results

Conclusion