Operational Parameters for the Superconducting Cavity Maser
Abstract
Tests of the superconducting cavity maser (SCM) ultra-stable frequency source have been made for the first time using a hydrogen maser for a frequency reference. In addition to characterizing the frequency stability, the sensitivity of the output frequency to several crucial parameters was determined for various operating conditions. Based on this determination, the refrigeration and thermal control systems of the SCM were modified. Subsequent tests showed substantially improved performance, especially at the longest averaging times. In frequency stability tests, characterization of the short term performance of the SCM was not possible due to hydrogen maser fluctuations, but for the longest measuring time the low SCM instabilities could be characterized. This was expected, since cryogenic cavity oscillators show unsurpassed performance for short measuring times. In initial tests, our measurements showed a frequency stability of about 2. 10-l4 for times between 30 and 3000 seconds. The long term stability (3000 a) is appraocimately 5 times better than we were previously able to measure. In order to better understand the limits to SCM stability we performed a detailed study of the dependence of the operating microwave frequency ( ~ 32. 69GHz) on: operational temperature, pump frequency, pump power, coupling strength and the bias field applied to the ruby maser. Of these, sensitivity to changes in temperature and pump power are crucial because of the great difficulty in stabilizing these two parameters. We discovered operational parameters for which both of these sensitivity coefficients approach zero, and have identified a sixth parameter, the temperature gradient across the oscillator, the effects of which severely compromised the effectiveness of our thermal regulation system.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1988
- Accession Number
- ADA506842
Entities
People
- D. M. Strayer
- G. J. Dick
- R. T. Wang
Organizations
- California Institute of Technology