Gyrokinetic modeling for basic turbulence experiments on the LAPD
Seminar Room 2, Newton Institute Gatehouse
We describe our gyrokinetic modeling efforts in support of planned basic turbulence experiments on the LAPD at UCLA. The focal point of this investigation is the fundamental building block of Alfvenic turbulence, the nonlinear interaction between two counter-propagating Alfven waves. Although the frequencies of Alfvenic fluctuations under typical LAPD operating parameters are often a substantial fraction (sometimes half or more) of the ion cyclotron frequency, our initial investigation has demonstrated that corrections to the predictions of the plasma behavior using gyrokinetics due to cyclotron effects are typically less than 10%. The intermediate collisionality of the LAPD plasma yields a much greater effect on the plasma dynamics and dissipation, yet a newly developed collision operator that has been implemented in the Astrophysical Gyrokinetics code AstroGK recovers the correct behavior in this challenging limit. I will describe current efforts underway to model the amplitude dependence of the nonlinear energy transfer rate; these results will help guide the design of the experiments to be performed in the laboratory.