Attempt to image and photograph an array of quantized vortex lines in rotating superfluid helium

The design of and experiments with a device to image and photograph the array of quantized vortices in rotating superfluid helium are described. Some theoretical background of vortices in helium is given, and a few previously attempted methods of imaging the array are discussed. The method used in this experiment involves the trapping of negative ions produced by an alpha source onto the vortex lines, resulting in an array of current filaments in the liquid helium. These current filaments terminate on a wire array (a close-packed bundle of fine, insulated copper wires) which acts like a fiber optics faceplate. On the opposite side of the wire array, the negative ions are ejected by ultraviolet light into a high vacuum region, where they are accelerated and focused by electric and magnetic fields onto a phosphor screen. The image on the phosphor screen is transmitted by a coherent fiber optics light pipe to an image intensifier and camera system. Resolution (60 points/mm2) and sensitivity (400 ions/sec/live) are sufficient to show the vortex array if stabilized. When rotated with superfluid helium, the device shows a uniform image of the wire array. A discussion of the results and possible improvements of the experiment are given. (auth)