PROTOTYPE EUV SPECTROMETER FOR OPERATIONAL MONITORING OF SOLAR EUV FLUX

SILICON PHOTODIODES WITH STABLE, THEORETICALLY PREDICTABLE QUANTUM EFFICIENCY IN THE XUV SPECTRAL RANGE HAVE BEEN RECENTLY DEVELOPED BY RAJ KORDE AND SCIENTISTS AT NIST. SCIENTISTS AT BESSY AND PTB IN GERMANY HAVE INDEPENDENTLY CONFIRMED THAT THE CALCULATED QUANTUM EFFICIENCY OF THESE XUV SILICON DIODES CAN BE USED FOR THE ESTABLISHMENT OF AN INDEPENDENT RESPONSIVITY SCALE IN THE XUV SPECTRAL RANGE. THESE DIODES HAVE BEEN SUCCESSFULLY USED BY THE SPACE SCIENCES GROUP AT THE UNIVERSITY OF SOUTHERN CALIFORNIA (USC) DURING 1989-1990 IN SOUNDING ROCKET EXPERIMENTS TO MEASURE THE ABSOLUTE SOLAR EUV FLUX. HERE, WE PROPOSE TO EXTEND THIS WORK TO BUILD A NORMAL INCIDENT SPECTROMETER WITH THE USE OF MULTI-ELEMENT SILICON PHOTODIODES ALONG WITH AN EUV TRANSMISSION GRATING. OWING TO ITS LOW WEIGHT, COMPACTNESS, AND EASE IN EXPERIMENTAL IMPLEMENTATION, THIS NOVEL SPECTROMETER WILL BE A VALUABLE TOOL ABOARD THE GOES SATELLITE TO CONTINUOUSLY MONITOR THE SOLAR EUV FLUX. DURING PHASE 1 OF THE CURRENTLY PROPOSED WORK, A SPECTROMETER BASED ON A 103 LINES/MM EUV GRATING ANDA 3 ELEMENT XUV SILICON PHOTODIODE WILL BE BUILT AND TESTED. DURING PHASE 2 OF THIS PROPOSAL, A HIGHER RESOLUTION VERSION OF THIS SPECTROMETER WILL BE DEVELOPED FOR THE PLANNED AND FUTURE MISSIONS.