Photo voltaic flares, among the many most intense explosive phenomena within the photo voltaic ambiance, launch huge quantities of vitality in a brief interval, leading to enhanced electromagnetic radiation throughout a number of bands. These occasions pose vital threats to Earth’s area atmosphere and human actions in area. Excessive-energy electrons accelerated throughout flares emit millimeter-wave radiation via gyrosynchrotron radiation, offering distinctive insights into the underlying magnetic fields and vitality launch processes (Fleishman et al 2018). Nonetheless, observational information within the millimeter-wave vary, notably above 20 GHz, have been severely missing. To deal with this hole, a analysis crew from the Institute of Area Sciences at Shandong College has efficiently developed a 50–55 GHz millimeter-wave radiometer spectrometer for photo voltaic flare detection, supplementing the related frequency band clean information.
Determine 1: The 50–55 GHz millimeter–wave radiometer spectrometer for photo voltaic flare detection is put in at an altitude of 4200 meters.
Millimeter-wave radiation emitted throughout photo voltaic flares is very environment friendly and delicate to high-energy electrons. This radiation not solely reveals details about the accelerated electrons but additionally offers distinctive insights into the magnetic discipline buildings and vitality launch processes throughout flares. Conventional photo voltaic radio devices primarily function under 18 GHz, with restricted information accessible above this frequency vary. This hole has hindered a complete understanding of high-energy electron acceleration and magnetic reconnection processes in photo voltaic flares. The brand new 50–55 GHz radiometer spectrometer goals to fill this observational void, providing unprecedented information for learning photo voltaic flares within the millimeter-wave vary.
Developed by the Institute of Area Sciences at Shandong College, the 50–55 GHz millimeter-wave radiometer spectrometer started common observations in October 2024. The system options a number of revolutionary designs and technical benefits: Excessive Sensitivity and Dynamic Vary: Geared up with a 50 cm diameter Cassegrain antenna, the system has a noise determine of lower than 2.5 dB and a dynamic vary exceeding 30 dB. It could detect each quiet photo voltaic indicators and intense flare bursts with excessive precision. Excessive Time Decision: The system achieves a time decision of 0.001–1 second, permitting it to seize speedy modifications throughout photo voltaic flares and supply detailed temporal data for flare research. Direct Detection Scheme: In contrast to conventional superheterodyne receivers, this method employs a direct detection methodology, eliminating nonlinear results and analog-device-induced noise(Chang et al. 2024). This design enhances the system’s dynamic vary and prevents sign saturation throughout intense flare occasions. Multichannel Parallel Acquisition: The system includes a custom-designed 4-channel parallel acquisition digital receiver with 32-bit decision. This design ensures excessive sensitivity and permits the detection of weaker flare bursts, offering extra complete information for photo voltaic flare analysis.
Determine 2: Detailed structure and sign routing of the system. It consists of 4 elements: antenna–feeder subsystem, analog entrance–finish subsystem, digital receiver subsystem, and higher pc subsystem. Introduced the design schemes of analog and digital receivers, in addition to the information processing work carried out throughout the discipline–programmable gate array.
In December 2024, the system efficiently captured the world’s first photo voltaic flare information within the 50 GHz band, recording an X1.5-class flare occasion. The info revealed radiation depth and polarization traits on this frequency vary, demonstrating the system’s functionality to watch high-energy electron emissions throughout flares. The noticed flare exhibited a peak flux density of roughly 450 SFU at 50.5–51.5 GHz, per typical detrimental optically skinny spectra. This achievement not solely fills the observational hole within the millimeter-wave vary but additionally offers essential information for establishing photo voltaic radiation fashions on this frequency band.
Determine 3：The remark outcomes of the photo voltaic flare on December 30, 2024 are displayed. And the spectral index map obtained from observations at 35–54 GHz reveals a major evolution of sentimental–onerous–more durable throughout flares.
The spectral indices derived from the flare information confirmed a “tender–onerous–more durable” sample in the course of the gradual, peak, and decay phases of the burst. This evolution suggests an accumulation of higher-energy electrons within the flare loops, a standard function in photo voltaic flares. The consistency between the brand new system’s information and people from different devices (such because the Chashan Broadband Photo voltaic millimeter spectrometer, CBSmm(Shang et al. 2022) confirms the reliability of the calibration scheme and lays the inspiration for future detailed calibration and information evaluation.
Based mostly on a not too long ago revealed article: Xu, Z. Zhao, Q. Liu, Q. Li, Z. Wu, G. Lu, Y. Su, Y. Chen, and F. Yan, A 50–55 GHz Millimeter-wave Radiometer Spectrometer for Photo voltaic Flare Detection, ApJS 279(1), 29 (2025), DOI: 10.3847/1538-4365/ade0b5
References:
Fleishman, G. D., Nita, G. M., Kuroda, N., et al. 2018, 301, ApJ, 859, 17
Chang, B. Wang, G. Lu, et al., 2024, ApJS, 272, 21
Shang,Ok. Xu,Y. Liu, et al., 2022,ApJS, 258,25
