Entwicklung und Charakterizierung des Ballon getragenen Instruments TELIS (TErahertz and submillimeter LImb Sounder): 1.8 THz Empfänger

Abstract

Research on ozone has increased since the mid-1970s at which the ozone depletion was discovered. Both observational data and laboratory studies are demanded in order to improve the understanding of the global climate change which yield better numerical models for predictions. Nevertheless, there is still lack of observational data for enhancing the understanding of the related atmospheric and chemical processes of stratospheric ozone. Over the years, many remote sensing instruments have been developed and used for observing the atmospheric trace gas distributions associated with e.g. ozone destruction in various latitudes. Since 2001, a balloon-borne instrument called TELIS (TErahertz and submillimeter LImb Sounder) is under development at the German Aerospace Center (DLR), and this instrument has already successfully been used for measuring atmospheric constituents within the lower stratosphere. The work of this thesis is dedicated to the development and characterization of a cryogenic heterodyne receiver of the TELIS instrument used for measuring the OH emission at a frequency of 1.8 THz. In the framework of this thesis, all major components of the 1.8 THz channel were individually characterized before they were installed together. The methods and results for developing and characterizing the 1.8 THz channel are described in this thesis. In addition, radiometric characterization of the receiver was done by gas cell measurements of methanol gas. The present work also includes the integration of the 1.8 THz receiver into the TELIS flight module cryostat, and putting the instrument into operation in scientific flight campaigns. The integration was successfully done since the end of 2006. The characterization after the integration was fully done during 2007/2008 which yields the sensitivity improvement of the 1.8 THz heterodyne receiver of about 70% with respect to the prototype developed in 2005. After a first test flight in Teresina, Brazil, in May 2008, the 1.8 THz receiver was improved and operated well during a second flight campaign in Kiruna, Sweden, in March 2009. Various important atmospheric constituents within the lower stratosphere, such as the profiles of OH, HO2, O3, H2O isotopologues and CO were measured by the 1.8 THz receiver. The performance of the 1.8 THz receiver and some DSB (quick-look) calibrated spectra from the Kiruna campaign (2009) are presented in this thesis.