High-resolution radiometers for solar flare activity
Current ground-based telescopes for solar flare observations can predict solar flares so that we may better guard against their effects. However, to enable greater understanding of the Sun on all spatial scales and complement ground-based solar research, more sensitive receivers are needed, especially in the sub-millimetre wavelengths. Even though the integration of radiometers in a silicon chip has been a subject of study since 2008, the implementation of such miniaturised radiometers at the Ka band for solar flare observation has never been proposed before. Low-cost micro-, nano- and pico-satellite missions can dramatically improve quantitative understanding of the Sun’s activity at the microwave range. Within the EU-funded project FLARES (System-on-chip millimeter-wave radiometers for space-based detection of solar flares), researchers successfully developed space-borne radiometers capable of measuring very-low-level microwave radiation. Implemented on a silicon chip, the newly developed receivers reliably detect low-intensity solar flares of about 100 times lower intensity than those detected by state-of-the-art technology. The millimetre-wave portion in the Ka band is closely linked to many events triggered by flares such as the correlation between gamma-ray emissions and flaring activity at 37 GHz. FLARES’ space-borne radiometer enables significant reductions in terms of weight, size and power consumption, all of which are equally important for space applications and especially for micro-, nano- or pico-low-Earth orbit satellite missions. Calibration circuitry, thermal stabilisation and analogue-to-digital converters were all integrated together into the receiver circuitry. The microwave radiometer, which can also be used for detecting solar flares in other frequency bands, represents a significant improvement with respect to state-of-the-art ground-based instruments for observing solar flares. It can also provide a good basis for further developments for both 1D and 2D solar observations when combined in focal plane arrays of system-on-chip radiometers.
Keywords
Radiometer, solar flare, microwave, FLARES, system-on-chip
