Abstract
<title>Abstract</title> <p>In this paper some spectral properties of a single Type III burst observed with PSP in the wide frequency range from 0.3 up to 19 MHz are studied. The velocity spectrum of different intensity levels of this burst was obtained and it showed that high and low velocities were associated with the leading and trailing edges of the burst correspondingly. It turned out that the velocity of the burst peak was about 0.6 times of maximal velocity as was predicted by the theory of beam-plasma structure formed during the propagation of fast electrons through plasma in the weak turbulence approximation. The drift rate dependences on frequency for different burst levels agreed well with the assumption that Type III electrons propagate in the coronal plasma following the Newkirk law n(r)=4.2∙10^4∙10^(4.32R_S/r) 〖cm〗^(-3) at distances up to r=5R_S, n(r)=2∙10^7∙〖(R_S/r)〗^2.6 〖cm〗^(-3) at distances from r=5R_S, to r=15R_S, and n(r)=9∙10^6∙〖(R_S/r)〗^2.3 〖cm〗^(-3) from r=15R_S to r=50R_S, where R_S is the solar radius. Also, we found the duration-frequency dependencies for this Type III burst. It appeared to be close to the Elgaroy-Lingstad dependence and we show that this dependence is defined by the dispersion of electron velocities in the beam-plasma structure. Because of wide frequency band of PSP observations, we were able to measure frequency widths of the burst at different frequencies. It is turned out that they are close to those obtained earlier in other frequency bands.</p>