The wave number spectrum (one-dimensional spectrum) of electrostatic potential fluctuations at sub-Larmor scales was measured in two-dimensional (2D) electrostatic turbulence in laboratory magnetized plasma. The spectrum at scales k⊥ρi>1, where k⊥ and ρi are the fluctuation wave number perpendicular to the magnetic field and ion Larmor radius, respectively, supports the existence of the k -10/3 inertial range of the entropy cascade induced by nonlinear phase mixing. This indicates agreement with a theoretical prediction [A. A. Schekochihin et al., Plasma Phys. Controlled Fusion 50, 124024 (2008)PPCFET0741-3335] and the result of a 2D gyrokinetic simulation [T. Tatsuno et al., Phys. Rev. Lett. 103, 015003 (2009)PRLTAO0031-9007]. The cutoff wave numbers of the spectrum, above which the entropy cascade is smeared by collisions, observed in this experiment were consistent with those in the theory.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)