A comparison of mean density and microscale density fluctuations in a CME at 10 R

[1] We have observed intensity scintillation (IPS) of the radio source 0854 + 201 at 8 GHz on August 2, 2000 during the passage of a coronal mass ejection (CME) across the line of sight. The source was at a distance of 10 R over the north solar pole. Simultaneous observations with the LASCO C3 instrument allow us to model the mean density Ne and the microscale density fluctuations dNewithin the CME.We find that Ne increased by a factor of 2.18 but dNe increased by only 1.76, so the ratio dNe/Ne is 19% smaller than in the preCME slow wind. During the passage of the CME a short burst of enhanced turbulence doubled the IPS variance but was not visible in the C3 images. This was likely caused by a thin flux tube crossing the line of sight. Detailed modeling indicates that the diameter of the tube was 41,000 km and its density was 14.5 times the CME density.