I have read about various variations of magnetic bottle fusion reactors for 50 years. No one seems to be able to predict the behavior of the plasmas well enough to get them to work. Since there is plenty of computers and money in the projects, obviously the equations are wrong.
I do not what but one thing is: Some books I looked at on the subject feel they do not need worry about relativity or the axial Doppler shift becuse they do not need relativistics temperatures to get fusion. But lot the products will be for a time at relativistic velocities.
The attached papers, in the form of PDF files, that the resultant of the axial transverse Doppler shifts and will have a big effects on Maxwell's equations. Even changing the dimensions.