Exotic Negative Carriers in Liquid Helium

Abstract

through second order; clearly the result is causal on the r 0 scale and acausal on the r 2 scale.The nonadiabatic approximation implies the use of the fully causal Green's function. 5 The results for the two-body correlation function G (x, x x , v, t) = G 1 can be extended to s bodies. Writing c + ...+ S G i+ F, *= i where the index c in the second term denotes combinations of s -1 indices in s -2 places, it can be shown by induction that the s-body correlation function satisfies [d/dt + v-v]K lt2r .. tS . x = source term involving lower-order correlations, where terms of magnitude € or smaller in the s-body and higher correlation functions have been dropped. From this equation, we see that the exact Green's function for the s-body corre-lation is causal and of the same form as for two bodies. Our previous remarks on the Bogoliubov and time-scales approximations also extend without difficulty.We have confirmed the existence of a new negative carrier of high mobility in superfluid helium, reported by Doake and Gribbon, and determined its zero-field mobility. We suggest that it may be the negative helium ion in a small cavity in the liquid. A series of carriers with mobilities between that of the "fast" and the "normal" (electron bubble) carrier is also shown to exist.

The effect of strong electric fields on exotic negative ions in He II: Possible evidence for the nucleation of charged vortex rings

“…We have also made measurements for values of E well below that of the "giant fall" in v which occurs at E cn for the normal ion. In agreement with the earlier work [3,4] we observe several quite distinct mobilities. As E is increased for E < E cn we find thatῡ(E) for the principal intermediate ions bends over and approaches the horizontal.…”

“…Although Doake and Gribbon were unable to ascertain the physical conditions needed to generate this mysterious entity reproducibly, Ihas and Sanders showed [3,4] soon afterwards that the vital factor apparently lay in the provision of an electrical discharge in the vapour above the surface of the liquid. The latter authors also discovered that the glow discharge source produces not only the normal and fast negative ions, but also (astonishingly) a large number of other types of negative ion with low-field mobilities lying intermediate between those of the fast and normal ions.…”

“…Alnoise from our relatively short cell is ly) rather poor, the drift velocity vof e ions quite eVidently decreases with ehaviour of this type is, of course, cent of that displayed by the charged rmed by normal ions, and it may thereed as an indication that intermediate form vortex rings. We have also made for values of E well below that of the v which occurs at E cn for the normal ent with the earlier work [3,4] we obuite distinct mobilities. As E is increased ?ig.…”

“…pected plethora of exotHe II constitutes an ineoretical problem. Alnormal negative ion is detail [2] the nature(s) ions remain(s) an enason for our continuing e experimental informaand we have therefore ignorance is that the available experimental information [1,3,4] is rather sparse; and we have therefore embarked on a research programme aimed at remedying this unsatisfactory situation. In this Letter, we report the preliminary results of what is believed to be the first experimental study to be made of the behaviour of the intermediate mobility ions in strong electric fields.…”

Cavitation of electron bubbles in liquid parahydrogen

“…We will refer to these structures as electron bubbles (e-bubbles). Many works have been devoted to measure the mobility of electron bubbles in liquid helium [1][2][3][4] and hydrogen [5][6][7][8][9].…”