Negative ion currents in turbulent counterflow of superfluid helium

The decay of negative ion currents in tubulent counter flow of superfluid helium as a function of heat flux, was studied to determine the dynamic properties of quantized vortex lines present in turbulent counterflow. A negative ion current builds up and decays much more slowly in the presence of turbulent counterflow than in quiescent Helium II. This can be understood if the ions are trapped and released by quantized vortex lines present in turbulent counterflow. Three features of the current decay were examined. The area under the extended current decay is a direct measure of the amount of charges trapped on vorticity at the time the ion current was turned off. This quantity depends on both the trapping and escape probabilities of ions. The time constant of the exponential part of the current decay indicates the rate at which ions are released from the vorticity.