Peijin ZhangUniversity of Helsinki | HY · Department of Physics
Peijin Zhang
Doctor of Philosophy
Working on methods of radio interferometry, solar radio wave propagation.
About
44
Publications
5,402
Reads
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158
Citations
Citations since 2017
Introduction
Mainly focus on the radio burst. Recently working on the ray tracing of the EM wave in the coronal.
Skills and Expertise
Additional affiliations
February 2022 - March 2022
September 2021 - December 2022
June 2019 - September 2019
Education
September 2013 - September 2017
Publications
Publications (44)
The electron-cyclotron maser is a process that generates the intense and coherent radio emission in the plasma. In this paper, we present a comprehensive parametric investigation on the electron-cyclotron-maser instability driven by non-thermal ring-beam electrons with intrinsic Alfvén waves, which pervade the solar atmosphere and interplanetary sp...
We design an event recognition-analysis system that can automatically detect solar type III radio burst and can mine information of the burst from the dynamic spectra observed by Nancay Decameter Array (NDA). We investigate the frequency drift rate of type III bursts and the speed of electron beams responsible for the generation of the bursts.
Seve...
Solar type III radio bursts are excited by electron beams propagating outward from the Sun. The flux of type III radio burst has a time profile of rising and decay phase at a given frequency, which has been actively studied since 1970s. Several factors that may influence the duration of a type III radio burst has been proposed. However, the major c...
Radio emission of the quiet Sun is considered to be due to thermal bremsstrahlung emission of the hot solar atmosphere. The properties of the quiet Sun in the microwave band have been well studied, and they can be well described by the spectrum of bremsstrahlung emission. In the meter-wave and decameter-wave bands, properties of the quiet Sun have...
Context. Solar radio bursts originate mainly from high energy electrons accelerated in solar eruptions like solar flares, jets, and coronal mass ejections. A subcategory of solar radio bursts with short time duration may be used as a proxy to understand the wave generation and propagation within the corona.
Aims. Complete case studies of the sour...
The "middle corona," defined by West et al. (2022) as the region between ~1.5-6 solar radii, is a critical transition region that connects the highly structured lower corona to the outer corona where the magnetic field becomes predominantly radial. At radio wavelengths, remote-sensing of the middle corona falls in the meter-decameter wavelength ran...
Radio spectroscopy provides a unique inspection perspective for solar and space weather research, which can reveal the plasma and energetic electron information in the solar corona and inner heliosphere. However, Radio-Frequency Interference (RFI) from human activities affects sensitive radio telescopes, and significantly affects the quality of obs...
NenuFAR is a new radio telescope covering the range 10 MHz to 85 MHz, implemented in France. It extends the capabilities of LOFAR toward the low-frequency range. The scientific goals are wide, from the dark ages of the universe and galaxies to pulsars and the search for exoplanets. This letter illustrates the capabilities of NenuFAR for solar studi...
Probing the solar corona is crucial to study the coronal heating and solar wind acceleration. However, the transient and inhomogeneous solar wind flows carry large-amplitude inherent Alfvén waves and turbulence, which make detection more difficult. We report the oscillation and propagation of the solar wind at 2.6 solar radii (Rs) by observation of...
The Sun is the source of different types of radio bursts that are associated with solar flares, for example. Among the most frequently observed phenomena are type III solar bursts. Their radio images at low frequencies (below 100 MHz) are relatively poorly studied due to the limitations of legacy radio telescopes. We study the general characteristi...
Context. The Sun is the source of different types of radio bursts that are associated with solar flares, for example. Among the most frequently observed phenomena are type III solar bursts. Their radio images at low frequencies (below 100 MHz) are relatively poorly studied due to the limitations of legacy radio telescopes.
Aims. We study the genera...
Probing the solar corona is crucial to study the coronal heating and solar wind acceleration. However, the transient and inhomogeneous solar wind flows carry large-amplitude inherent Alfvén waves and turbulence, which make detection more difficult. We report the oscillation and propagation of the solar wind at 2.6 solar radii (Rs) by observation of...
Observations of interplanetary scintillation (IPS - the scintillation of compact radio sources due to density variations in the solar wind) enable the velocity of the solar wind to be determined, and its bulk density to be estimated, throughout the inner heliosphere. A series of observations using the Low Frequency Array (LOFAR - a radio telescope...
Magnetic reconnection preferentially takes place at the intersection of two separatrices or two quasi-separatrix layers, which can be quantified by the squashing factor Q , whose calculation is computationally expensive due to the need to trace as many field lines as possible. We developed a method (FastQSL) optimized for obtaining Q and the twist...
Type-IV radio bursts have been studied for over 50 years. However, the specifics of the radio emission mechanisms is still an open question. In order to provide more information about the emission mechanisms, we studied a moving Type-IV radio burst with fine structures (spike group) by using the high-resolution capability of the Low-Frequency Array...
Observations of interplanetary scintillation (IPS – the scintillation of compact radio sources due to density variations in the solar wind) enable the velocity of the solar wind to be determined, and its bulk density to be estimated, throughout the inner heliosphere. A series of observations using the Low Frequency Array (LOFAR - a radio telescope...
Type IV radio burst has been studied for over 50 years. However, the specifics of the radio emission mechanisms is still an open question. In order to provide more information about the emission mechanisms, we studied a moving type IV radio burst with fine structures (spike group) by using the high resolution capability of Low-Frequency Array (LOFA...
Magnetic reconnection preferentially takes place at the intersection of two separatrices or two quasi-separatrix layers, which can be quantified by the squashing factor Q, whose calculation is computationally expensive due to the need to trace as many field lines as possible. We developed a method (FastQSL) optimized for obtaining Q and the twist n...
Radio emission of the quiet Sun is considered to be due to thermal bremsstrahlung emission of the hot solar atmosphere. The properties of the quiet Sun in the microwave band have been well studied, and they can be well described by the spectrum of bremsstrahlung emission. In the meter-wave and decameter-wave bands, properties of the quiet Sun have...
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Type II radio bursts are thought to be produced by shock waves in the solar atmosphere. However, what magnetic conditions are needed for the generation of type II radio bursts is still a puzzling issue. Here, we quantify the magnetic structure of a coronal shock associated with a type II radio burst. Based on multiperspective extreme-ultraviolet ob...
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Type II radio bursts are thought to be produced by shock waves in the solar atmosphere. However, what magnetic conditions are needed for the generation of type II radio bursts is still a puzzling issue. Here, we quantify the magnetic structure of a coronal shock associated with a type II radio burst. Based on the multi-perspective extreme-ultraviol...
The ESA's Mars Express solar corona experiments were performed at two solar conjunctions in the years 2015 and 2017 by a number of radio telescopes in the European VLBI Network. This paper presents the methods to measure the frequency and phase fluctuations of the spacecraft radio signal, and the applications to study the characteristics of the pla...
The ESA's Mars Express solar corona experiments were performed at two solar conjunctions in the years 2015 and 2017 by a number of radio telescopes in the European VLBI Network. This paper presents the methods to measure the frequency and phase fluctuations of the spacecraft radio signal, and the applications to study the characteristics of the pla...
The observed features of the radio source indicate that the waves of solar radio bursts are convoluted with complex propagation effects. In this work, we perform ray-tracing simulations on radio wave transport in the corona and interplanetary region with anisotropic electron density fluctuations. For the first time, the variation of the apparent so...
The observed features of the radio sources indicate complex propagation effects embedded in the waves of solar radio bursts. In this work, we perform ray-tracing simulations on radio wave transport in the corona and interplanetary region with anisotropic electron density fluctuations. For the first time, the variation of the apparent source size, b...
We present the observations of two type III solar radio events performed with LOFAR (LOw-Frequency ARray) station in Bałdy (PL612), Poland in single mode. The first event occurred on 20th August 2017 and the second one on 9th September 2017. Solar dynamic spectra were recorded in the 10 MHz up to 90 MHz frequency band. Together with the wide freque...
Radioheliograph images are essential for the study of solar short term activities and long term variations, while the continuity and granularity of radioheliograph data are not so ideal, due to the short visible time of the Sun and the complex electron-magnetic environment near the ground-based radio telescope. In this work, we develop a multi-chan...
Since the traditional detection methods cannot accurately detect, determine and extract weak signals, the extreme sensitivity of chaotic systems to initial values is used for weak signal detection using a memristor-based chaotic system. Then, in order to find out all kinds of static nonlinear circuits suitable for Chua’s circuit with identical para...
The radioheliograph image is essential for the study of solar short term activities and long term variations, while the continuity and granularity of radioheliograph data is not so ideal, due to the short visible time of the sun and the complex electron-magnetic environment near the ground-based radio telescope. In this work, we develop a multi-cha...
Context. Solar radio bursts originate mainly from high energy electrons accelerated in solar eruptions like solar flares, jets, and coronal mass ejections. A subcategory of solar radio bursts with short time duration may be used as a proxy to understand the wave generation and propagation within the corona. Aims. Complete case studies of the source...
Solar S-bursts are short duration (< 1 s at decameter wavelengths) radio bursts that have been observed during periods of moderate solar activity, where S stands for short. The frequency drift of S-bursts can reflect the density variation and the motion state of the electron beams. In this work, we investigate the frequency drift and the fine struc...
A second peak in extreme ultraviolet sometimes appears during the gradual phase of solar flares, which is known as EUV late phase (ELP). Stereotypically ELP is associated with two separated sets of flaring loops with distinct sizes, and it has been debated whether ELP is caused by additional heating or extended plasma cooling in the longer loop sys...
Solar type III radio bursts are excited by electron beams propagating outward from the Sun. The flux of type III radio burst has a time profile of rising and decay phase at a given frequency, which has been actively studied since 1970s. Several factors that may influence the duration of a type III radio burst has been proposed. However, the major c...
Forward modeling of the radio source track of type III radio burst
In this work, we propose a forward-modeling method to study the trajectory and speed of the interplanetary (IP) Type-III radio burst exciter. The model assumes that the source of an IP Type-III radio burst moves outward from the Sun following the Parker spiral field line. Using the arrival time of the radio waves at multiple spacecraft, we are able...
In this work, we propose a forward-modeling method to study the trajectory and speed of the interplanetary (IP) Type-III radio burst exciter. The model assumes that the source of an IP Type-III radio burst moves outward from the Sun following the Parker spiral field line. Using the arrival time of the radio waves at multiple spacecraft, we are able...
The table contains 1389 records, each record includes the event observation time, the starting/stopping frequencies and the average frequency drift rate of a type III solar radio burst. The events were observed by The Nancay Decameter Array (NDA) in the frequency range 10-80MHz between 2012 and 2017.
Purpose
This paper aims to introduce a novel four-dimensional hyper-chaotic system with different hyper-chaotic attractors as certain parameters vary. The typical dynamical behaviors of the new hyper-chaotic system are discussed in detail. The control problem of these hyper-chaotic attractors is also investigated analytically and numerically. Then...
The sun is the closest star from the earth. The solar activity can influence the solar terrestrial and the high-altitude atmosphere of the earth. Because of the absorption of the electromagnetic waves in the specific band, the ground observation of the sun is mainly for two frequency-bands: visible and radio.The radio observation is mainly in the f...
Questions
Question (1)
When will the data product online for researchers to use?
Projects
Projects (2)
http://www.issibern.ch/teams/lofar/
The new observations at sub-second scales require new models and a re-thinking of the current understanding of the non-thermal processes in the outer corona. In the view of the unprecedented radio data, we plan to complement these radio observations with the data from a suite of spacecrafts (RHESSI, SOHO, STEREO, SDO, Fermi) to gain a new level of understanding of the non-thermal processes in the outer corona.
