X-Ray Calibration Facility (XRCF)

History of the XRCF

The original X-ray Calibration Facility was first constructed at Marshall Space Flight Center in the middle of the 1970's for the ground testing and calibration of the High Energy Astrophysics Observatories. The testing required a near parallel beam of soft X-rays in a vacuum environment. This first facility consisted of a guide tube measuring 305 meters (1000 ft.) long having a diameter of 0.9 meters (1ft.) and an instrument chamber measuring 6.2 meters (20.5 ft.) in diameter by 6.1 meters (20 ft.) in length. The facility was successfully operated in 1977.

From 1977 through 1989 the XRCF was used for testing and calibrating ten sounding rocket X-ray payloads, a grating spectrometer for the Geosynchronous Earth Orbiting Satellite (GEOS), the Solar-A Soft X- ray Imager (Solar-A), and preliminary components developed for the Advanced X-ray Astrophysics Facility (AXAF)

Additionally, in support of the Hubble Space Telescope (HST) program, a vacuum bakeout of the Focal Plane Structure was accomplished in the Instrument Chamber.

In late 1989, the facility was upgraded in size and capability to perform X- ray calibrations of the AXAF mirrors and science instruments. The modifications came in two phases. Phase I required approximately two years to complete and improved the basic structural, vacuum pumping, and X-ray generation capabilities. Three major contracts issued for the Phase I construction are:

Universal Construction Company (UCC) received the contract to modify the facility.

The contract for the new vacuum chamber was awarded to Pitt-DeMoines (PDM), who fabricated the stainless steel vessel measuring 22.9 meters (75 ft) long by 7.3 meters (24 ft) in diameter. The chamber was built in Pittsburgh, Pennsylvania and then transported by barge to Huntsville.

The contract for the additional guide tube was awarded to CVI, Inc., who provided approximately 91 meters (300 ft) of 1.5 meter (5 ft) diameter tube and 122 meters (400 ft) of 1.2 meter (4 ft) diameter tube.

All contract work for Phase I was essentially completed by the summer of 1991 and a Verification Engineering Test Article (VETA) was calibrated for the AXAF telescope in September, 1991. The VETA consisted of the largest pair of the four AXAF mirrors assembled in a test fixture. It demonstrated that the X-ray optics surpassed the requirements for the AXAF program, resulting in the continuation of AXAF development.

Phase II of the construction to prepare the XRCF facility for AXAF calibration was begun in late 1992 with a contract to Sauer, Inc. This phase included the addition of cryogenic pumps to the Instrument Chamber and Guide Tube, the completion of the Class 2000 Clean Room and Dressing Area, the installation of a pumped liquid nitrogen system for the cryogenic shrouds, and various other building enhancements such as the addition of an elevator and the completion of the third floor experimenter office space. This second phase of construction was completed in early 1994 and the facility was turned over to the AXAF testing organization.

In addition to the complex facility activation process; design, fabrication and installation of the Thermal Control System, which includes a complete cryogenic shroud, heater panels, and electronic control system, is also in progress. The cryogenic panels, fabricated by Process Systems , Inc. (PSI) (define them) The heater panels were fabricated in-house at MSFC. In addition, the four X-ray generation systems have been installed on translation tables allowing researchers to quickly reconfigure the source during the calibration process. Approximately one year will be required to test and characterize these four X-ray sources prior to arrival of the AXAF mirrors and science instruments.