The total solar irradiance in space research problems

Аuthors

Gobor I. N.^1*, Dipner A. A.^2**, Ozolin V. V.^3***

1. National Research Institute for Physicotechnical and Radio Engineering Measurements, Mendeleevo, Moscow region, 141570, Russia
2. NTC Expertcenter, Mendeleevo, Moscow region, 141570, Russia
3. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: test-center@vniiftri.ru
**e-mail: dipner.a@gmail.com
***e-mail: ozolinv58@gmail.com

Abstract

In this article it is shown that the accuracy of pyrheliometers installed in artificial Earth satellites and applied for measurement of solar constant or total solar irradiance (TSI) is insufficient for measurement of long- term variations of TSI at the level of 0, 1% per years. The calibration method of pyrheliometers by feeding on them monochromatic radiation of several lasers with stable energy characteristics and different wavelengths is considered. Three methods of accurate laser power measurement are debated: with the help of cryogenic vacuum radiometer, silicon planar photodiode with additional transparent electrode on illuminated area and method of laser PIN- photodiode comparison.

The relative error of a measurement of laser power by the first method is 0,01 — 0,03%, and it is estimated by the computational way. If one applies silicon planar photodiodes, it strives growths of quantum efficiency up to 100% (on the statement of authors) by the feed of growing potential on the transparent electrode. Some independent researchers consider that the relative error of a measurement of a laser power by the given method could make up 0, 3%. The third method is based on the application of planar photodiodes with external or embedded temperature detector.

If one feeds the calibrated electric power on such photoconvertor, then it is translated into heat flow copying as on coordinates as at whiles the heat flow induced by dissipation of radiation in photoconvertor due to a drift of charge carriers initiated by the radiation.

Because of this the error of laser power measurement drops to 0, 001%.

Two methods for control of residual connected with inequivalence of optical radiation and electric current conversion in heat flow are pointed out.

First is based on the use of two operating modes of photodiode — short circuit and idle pitch, second is realized by the variation of thermal environment characteristics near illuminated surface of photodiode.

То increase the right verification of TSI variations it is offered to create an imitator of TSI and to strive a suitable reproducibility of Earth measurements in conditions analogous to orbital ones. The principle possibility of application of TSI monitoring results for forecasting flares of solar activity is mentioned, which should increase the reliability of aerospace electronic systems.

Keywords:

total solar irradiance, pyrheliometer, laser comparator, solar simulator standard

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