After three years’ efforts of scientists, the first mm-wave solar microwave spectral observing system (35-40 GHz) in the solar radio community has been able to make routine observations in Chashan Observatory (CSO), Shandong University. This spectrometer was developed by the Laboratory for Electromagnetic Detection Technology (LEAD, chief scientist Dr Chen Yao, chief director Dr Yan Fabao), Institute of Space Sciences, Shandong University. Recently, the paper introducing this system (A Broadband Solar Radio Dynamic Spectrometer Working in Millimeter-Wave Band) was published in the Astrophysical Journal Supplement Series (IF: 8.1), and became the first academic paper on solar radio observation instrument in the microwave band published in the AAS.
This system has significant value in both space activities and scientific research as it is the first solar-dedicated spectrometer working in such high-frequency range and the only instrument that can provide routinely solar microwave continuum in the optically thin regime. The observing result can be used to monitor the solar eruptions which are the sources of nearly all catastrophe events in solar-terrestrial space, and help to develop space weather forecast system to safeguard aerospace activities of humankind. Meanwhile, the science data is of importance in the understanding of the physical process during solar flares. And it can provide unique information on magnetic fields and energetic particles in the eruption regions. According to these data, flare triggering and eruption mechanisms may be derived together with multi-wave observations.
In the past, most solar radio observing systems work below 18GHz with several exceptions such as observations at 35 and 80 GHz of the NoRP in Japan. A full coverage of microwave dynamic spectrum, especially in the optically thin regime (above~15 GHz) has been demanded by the solar radio community since the last century. Based on these considerations, the LEAD is devoted to developing this ground-based observing system and expects that this system could play a significant role in the coming maximum of the 25th solar cycle. This spectrometer (35-40 GHz, see the prototype in panel a in Figure below) can provide routine observation of the Sun with a time resolution of 5ms – 1.3s, and spectral resolution of 153 kHz (scan of the Sun is shown in panel b (Figure below). The performance of the system is as follows: noise factor of ~300K and system linearity of >0.9999.
Figure: The prototype of the system (a) and the observations of the scanning Sun (b).
The LEAD, as a part of Shandong University space science climbing project team, has been a model of interdisciplinary laboratory since its establishment in early 2018. The laboratory aims to develop large-scale, urgently needed basic scientific research equipment for space disciplines in China, and has undertaken several key instrument R & D projects such as the NNSFC major research instrument development projects, NNSFC major projects, the National Major Science and Technology Infrastructure - Meridian Project Phase II, pre-installation and pre-research of the Ministry of Education, and other teachings as well as research projects.