11:45 AM - 12:00 PM
[PEM14-05] Next generation solar wind observation system: science requirements and pathfinders.
Keywords:solar wind, CME, radio observation
Interplanetary scintillation (IPS) is a radio scattering phenomenon caused by the disturbances in the solar wind. The IPS observation using ground-based radio telescopes has been an important technique to investigate the global structure of the heliosphere. Nagoya University have observed the solar wind velocity and density irregularities for several decades using large radio telescopes at 327 MHz. In this study, we investigated the science requirements and design of next generation IPS observation instruments, and developed their pathfinders.
The main scope of this research is to elucidate the acceleration mechanisms of the solar wind. To do that, the relationship between the accelerated solar wind velocity and the magnetic field structure of its source region should be derived. We can derive the global structure of the solar wind from the IPS data using the tomography method. However, the spatial resolution of the solar wind distribution projected on the solar surface is not enough to distinguish its source structures. Therefore, we consider a new solar wind observation system that can observe multiple directions simultaneously by constructing a 2D flat phased-array antenna system consisting of multiple dipole antennas, and installing digital phased-array devices. The multidirectional simultaneous radio scintillation observation using this system enables the solar wind observation 10 times as much as the conventional radio instruments have been done, which will give enough spatial resolution of the solar wind distribution.
We also developed a proto type of the digital phased array instrument. This instrument has 8 analog-digital converters (ADCs), field-programmable gate array (FPGA), and 10-Gbit Ethernet output. This system enables us to measure four beams simultaneously by processing four types of different beamforming in parallel. We also added an automated calibration sequence to the FPGA. This sequence makes a calibration table that compensates an amplitude and phase differences of the 8 signals. By Appling this table, we can quickly calibrate the amplitude and phase differences of antennas and receivers. In the laboratory experiments, we confirmed that the calibration system works as expected.
The main scope of this research is to elucidate the acceleration mechanisms of the solar wind. To do that, the relationship between the accelerated solar wind velocity and the magnetic field structure of its source region should be derived. We can derive the global structure of the solar wind from the IPS data using the tomography method. However, the spatial resolution of the solar wind distribution projected on the solar surface is not enough to distinguish its source structures. Therefore, we consider a new solar wind observation system that can observe multiple directions simultaneously by constructing a 2D flat phased-array antenna system consisting of multiple dipole antennas, and installing digital phased-array devices. The multidirectional simultaneous radio scintillation observation using this system enables the solar wind observation 10 times as much as the conventional radio instruments have been done, which will give enough spatial resolution of the solar wind distribution.
We also developed a proto type of the digital phased array instrument. This instrument has 8 analog-digital converters (ADCs), field-programmable gate array (FPGA), and 10-Gbit Ethernet output. This system enables us to measure four beams simultaneously by processing four types of different beamforming in parallel. We also added an automated calibration sequence to the FPGA. This sequence makes a calibration table that compensates an amplitude and phase differences of the 8 signals. By Appling this table, we can quickly calibrate the amplitude and phase differences of antennas and receivers. In the laboratory experiments, we confirmed that the calibration system works as expected.