So basically you're saying that the imaginary term in your dispersion relation is comparatively larger for the lower harmonics (including the fundamental?)? Yeah, I totally wanna see what assumptions you put into it, scan away, when you get a chance.

I'll ruin one nasty surprise for you right now: In far too many occasions, there's nothing "intuitive" about the way plasma waves behave. And in far too many occasions, sometimes it seems almost unknowable. People do a lot of plugging and chugging. Some real genius goes into analytic approaches to simplifying the results of working in a particular regime or field topography, etc. etc. into an expression palatable for computations. A cohesive physical interpretation of the results is another rabbit hole.

Right now, I'm working with anisotropies in electron velocity (phase) space (density) and applying the WHAMP model to see if it'll reproduce the waves we're seeing (some people seem to use the words in the parentheses, some don't). But the space plasma regime I'm working in is regrettably far from that of reactors :(. Still, let some of them words cook your google/noodle.

Plasma is also notorious for nonlinear effects. That's part of the reason why they'll kick off a run of the engine, and even if they program in the exact same initial conditions/settings for their equipment on the next run, they hardly ever recover an appreciably identical result (obviously you know this, just translating for posterity). Like we've said before (I think?), nonlinearity seems to be a mathematical predictor of turbulence. Which seems to be somewhat ubiquitous to plasma