Engineering topics

Fowler, Walter

Publications and source records attributed to Fowler, Walter.

3 records

NASA NTRS1992

The simulated space proton environment for radiation effects on Space Telescope Imaging Spectrograph (STIS)

The space telescope imaging spectrograph (STIS) is a second generation instrument planned for the Hubble Space Telescope (HST) which is currently in orbit. Candidate glasses and other transmitting materials are being considered for order sorters, in-flight calibration filters, detector windows, and calibration lamps. The glasses for in-flight calibration filters showed significant drop in UV transmission, but can probably still be used on STIS. The addressed topics include the Hubble radiation environment, simulation of orbital exposure at Harvard Cyclotron Laboratory, measurement of spectral transmission, and comments on individual samples.

Becher, Jacob↗

NASA NTRS1990

Radiation damage in a Tektronix 512 CCD

A Tektronix CCD was subjected to a proton beam. Comparisons were made of the CCD characteristics before, during, and after radiation. Gain and readout noise were not affected and charge transfer efficiency, full well, and dark current were. Permanent CTE damage resulted immediately upon radiation, but full well damage developed two days after radiation, while the dark current showed signs of recovery before permanent damage occurred. Histogram analysis showed that the most spiky-type behavior resulted from damage to defects existing in the CCD before radiation.

Brown, Larry W.↗

NASA NTRS1988

Fabrication of MgF2 and LiF windows for the Hubble Space Telescope Imaging Spectrograph

Two prototype test windows (MgF2 and LiF) to be used on the 75-mm UV MAMA detector tubes for the Hubble Space Telescope Imaging Spectrograph are described. The spatial and optical constraints of this instrument dictate that the thickness of the window materials be no greater than 2-3 mm to achieve a minimum 50-percent transmission at hydrogen Lyman alpha (121.6 nm), and that the window must be domed to minimize optical aberrations and provide structural strength. The detector window has an input diameter of about 100 mm with a radius-of-curvature of 70 mm. The manufacturing processes involved in the fabrication of these windows is discussed, as well as test programs (optical and structural) to be performed at Goddard Space Flight Center.

Gormley, Daphne↗