Quasi-Optical SIS Receivers and Astrophysical Observations at Submillimeter Wavelengths

Details Quasi-Optical SIS Receivers and Astrophysical Observations at Submillimeter Wavelengths Quasi-Optical SIS Receivers and Astrophysical Observations at Submillimeter Wavelengths

Jan 1993

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993phdt........63b&link_type=abstract

Thesis (PH.D.)--CALIFORNIA INSTITUTE OF TECHNOLOGY, 1993.Source: Dissertation Abstracts International, Volume: 54-04, Section: B

Astronomy and Astrophysics

Astronomy

3

Sis Receivers

Scientific paper

This thesis describes the development of a new generation of quasi-optical submillimeter wave receivers aimed at future integrated array receivers and presents astronomical observations of neutral atomic carbon (C scI) taken with a single element of such a new receiver in the submillimeter wavelength band. An initial receiver design is presented that revealed two main problems with the design of quasi-optical receivers: Poor coupling of the receiver to the telescope and the impedance mismatch of the SIS detector to the planar antenna. A novel antenna design, called the hybrid antenna, with excellent beam patterns and simultaneously high aperture efficiencies solved the coupling problem. The hybrid antenna is diffraction limited, space efficient in an array due to its high aperture efficiency, and is easily mass produced. Using a novel superconducting transmission line circuit, called the end -loaded-stub, integrated with the Nb/AlO_ {x}/Nb SIS detector and the planar feed of the hybrid antenna, a good match was obtained from 200 GHz to 475 GHz with noise temperatures (DSB) of about 200 K. The combination of a hybrid antenna with the integrated tuning circuit lays the foundation for the development of integrated SIS focal plane receiver arrays. Observations of the C scIrm(^3P _1to ^3P_0) line at 492 GHz on large and small scales in the galaxy IC 342 and Orion (OMC-1), respectively, were made at the Caltech Submillimeter Observatory, which represent the first extragalactic and high spatial resolution submillimeter studies of C scI. A strong correlation with CO is established on large scales. On small scales C scI is found to be widespread with slight enhancements in photo-dissociation regions (PDRs) but its abundance drops sharply in the cores of condensations. A revised ion chemistry model of molecular clouds with external UV illumination matched the data well. It is suggested that the C scI emission emanates from the bulk of gas in low to moderate density molecular clouds and that it is a more important coolant there than CO. This is in contrast to previous PDR models that only had significant neutral carbon abundances in a thin transition layer on the surface of molecular clouds irradiated by UV.

Affiliated with

Also associated with

No associations

Rating

Quasi-Optical SIS Receivers and Astrophysical Observations at Submillimeter Wavelengths does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Quasi-Optical SIS Receivers and Astrophysical Observations at Submillimeter Wavelengths, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quasi-Optical SIS Receivers and Astrophysical Observations at Submillimeter Wavelengths will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1264571