We present extensive stimulated Brillouin scattering (SBS) results from experiments and modeling for four different photonic crystal fibers (PCFs) with core diameters ranging from 8 to 1.7 m. These results reveal several SBS characteristic features of small-core PCFs, high thresholds, and acoustic peaks, which are due to their antiguiding nature and highly multimode acoustic character. The nature of what we believe to be new acoustic modes is examined in the light of the large variations observed in the Brillouin gain, Brillouin threshold, and Brillouin shift with decreasing core diameter and optical wavelength.

Stimulated Brillouin scattering (SBS) generated from noise in small-core photonic crystal fibers (PCFs) exhibits a strong dependence on pump polarization. The polarization dependence of two small-core PCFs is investigated, yielding unexpected results. Both fibers exhibit birefringence resulting in a 90°polarization dependence for the SBS and a 3 dB difference in the SBS threshold between polarizations corresponding to minimum and maximum SBS, respectively. Surprisingly, the transmission of the smaller-core fiber also exhibits a 180°p olarization dependence at lower powers due to polarization-dependent loss.

Improved models are developed for integrated simulations of pedestal formation and edge localized mode (ELM) cycles at the edge of H-mode tokamak plasmas. The H-mode pedestal is formed in the simulations when flow shear and magnetic shear reduce the transport driven by drift modes at the edge of the plasma (Pankin A Y et al 2005 Plasma Phys. Control. Fusion 47 483). A large part of the flow shear is produced by the diamagnetic drift and the poloidal velocity, which is computed using a neoclassical model. Ion thermal transport is reduced to near the neoclassical level while electron thermal transport is reduced to the electron temperature gradient mode transport. A relatively large current density is driven in the pedestal by the bootstrap current. If the heating power is large enough, the pedestal growth is limited by ELM crashes, which are triggered by ideal MHD instabilities. Integrated simulations using these improved models are validated by comparing the simulation results with data for plasma profiles during the pedestal formation and with data for the ELM crash frequency. Simulations using the validated model are carried out for 31 Inernational Profile Database DIII-D and JET discharges.

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