Tests of Fiber Optic Cables at 300 and 4.2K

摘要

Strange cavity lights have been observed in Superconducting Radio Frequency (SCRF) Cavities. In order to understand this phenomenon a spectral analysis of the light is necessary. However, the extreme conditions presented within the cavity require the equipment to function at cryogenic temperatures. Ocean optics P600 UV/VIS fiber optic cables were studied at 300 K and 4.2 K to determine whether or not they would be appropriate for cryogenic temperatures. At 300 K the performance of different lengths of cable, the effect of a lens and the effect of a junction were investigated by taking spectra of red, green, and yellow LEDs at a variety of distances from where the source and the cable/spectrometer were aligned. It was found that there was significant attenuation of the signal between the spectrometer alone and the spectrometer with any combination of cables. The lens reduced the number of locations where a readable signal was produced, but the intensity increased greatly when the lens was aligned with the light source. The junction did not seem to make a difference except when there was a large angle between the light source and the cable. At 4.2 K a 4 m cable and a lens were submerged in liquid Helium to test their capabilities at cryogenic temperatures. The fiber optic cable was found unsuitable for use as it did not function at 4.2 K, and the signal was essentially lost. However, the lens survived.