This is one of the first ever papers on EVO's (AKA Plasmoids) by Winston H Bostick -ex Manhattan Project AFAIK - who was working on this in the mid-1950's and beyond. He cites several of his other papers on the topic, and the paper also includes a postscript verbatim discussion between the author, Hannes Alfven, Blackett and a few others.
The paper itself runs to 11 pages and provides both the math, the images and a number of interesting diagrams.