Coronal Diagnostics Via Modelling Periodic-Beaded Stripes of Solar Radio Bursts

TL;DR

This paper introduces a new spectral structure called periodic beaded stripes in solar radio bursts, develops a method to analyze their physical conditions, and uses DPR instability modeling for coronal diagnostics.

Contribution

It reports additional observations of these stripes, proposes a quantitative analysis method, and establishes a DPR-based framework for solar coronal diagnostics.

Findings

Periodic stripes occur post-flare with complex magnetic configurations.

Stripe modulation timescales are around 0.1 seconds.

Modeling constrains magnetic field to 0.2-1.7 G and plasma density to (1-7) × 10^8 cm^-3.

Abstract

Using high-resolution data from the Chashan Broadband Solar radio spectrometer at meter wavelengths (CBSm) of the Chinese Meridian Project-Phase II (CMP-II), Li et al. (2025) identified a novel fine spectral structure of solar radio bursts, termed periodic beaded stripes, and proposed a generation mechanism. Here we report additional events and develop a quantitative method to determine the physical conditions in the emission region. Periodic stripes tend to occur in the post-phase of flares and are associated with complex magnetic configurations. They repeat on sub-second timescales and show $\sim$0.1 s bead-like modulations, often accompanied by low-frequency absorptions. Modeling the chained stripes with linear kinetic theory of the double plasma resonance (DPR) instability constrains the source-region magnetic field to 0.2-1.7 G and the plasma density to (1-7) $\times 10^8$ cm $^{-3}$. The former follows the drift of individual stripes, and the latter tracks the overall trend. This study summarizes the key properties of periodic beaded stripes and establishes a quantitative DPR-based framework for coronal diagnostics.