Understanding the core density profile in TCV H-mode plasmas

Results from a database analysis of H-mode electron density profiles on the Tokamak \`a Configuration Variable (TCV) in stationary conditions show that the logarithmic electron density gradient increases with collisionality. By contrast, usual observations of H-modes showed that the electron density profiles tend to flatten with increasing collisionality. In this work it is reinforced that the role of collisionality alone, depending on the parameter regime, can be rather weak and in these, dominantly electron heated TCV cases, the electron density gradient is tailored by the underlying turbulence regime, which is mostly determined by the ratio of the electron to ion temperature and that of their gradients. Additionally, mostly in ohmic plasmas, the Ware-pinch can significantly contribute to the density peaking. Qualitative agreement between the predicted density peaking by quasi-linear gyrokinetic simulations and the experimental results is found. Quantitative comparison would necessitate ion temperature measurements, which are lacking in the considered experimental dataset. However, the simulation results show that it is the combination of several effects that influences the density peaking in TCV H-mode plasmas.Comment: 23 pages, 12 figure

A Comparison of Paralichthid Flounder Size-Structure in Northwest Florida Based on Trammel Net Catches Adjusted for Mesh Selectivity and Collection by SCUBA Divers

By applying a selectivity model for trammel net catches of Gulf flounder, we found that the resulting adjusted length distribution was similar to the offshore diver-sampled length distribution. We found two dominant size modes that seem to be consistent inshore and offshore, a lower mode composed of males and females and an upper mode composed exclusively of females. Southern flounder demonstrated a lower mode of males and small females but also showed larger females and possibly multiple-size modes after trammel net captures were adjusted for size selectivity. The two species showed very similar values for 91 (91 = 76.2-79.2), a coefficient affecting the mode of the gamma function used for selectivity. Our findings support the idea that the initial approximation of the mesh selectivities may be simple and could be based on parameters determined from related species. Gulf flounder were more abundant in the trammel net catch than were southern flounder, atid Gulf flounder comprised 80% of the net catches but was the only paralichthid flounder we collected offshore. Because southern flounder have been reported offshore from similar depths and habitats along the southeastern U.S. coast, partitioning of spawning habitat may be occurring in our area