Deriving Large Coronal Magnetic Loop Parameters Using LOFAR J Burst Observations

Abstract Large coronal loops around one solar radius in altitude are an important connection between the wind and low corona. However, their plasma properties ill-defined, as standard X-ray UV techniques not suited to these low-density environments. Diagnostics from type J radio bursts at frequencies above 10 MHz ideally understand loops. Despite this, J-bursts less frequently studied than III cousins, part because curvature of loop makes them unsuited for using density models. We used LOw-Frequency-ARray (LOFAR) Parker Solar Probe (PSP) dynamic spectrum identify 27 during a noise storm observed on April 2019. found that exciter velocities were similar, implying common acceleration region injects electrons along open closed magnetic structures. describe novel technique estimate model J-burst spectra, finding typical apex altitudes 1.3 radius. At this altitude, average scale heights 0.36 radius, temperature was 1 MK, pressure $0.7~\text{mdyn}\,\text{cm}^{-2}$ 0.7 mdyn cm − 2 , minimum field strength 0.13 G. discuss how parameters compare with much smaller