Microinstabilities in weak density gradient tokamak systems

Global Approach to the Spectral Problem of Microinstabilities in Tokamak Plasmas Using a Gyrokinetic Model

Ion temperature gradient (ITG) -related instabilities are studied in tokamak-like plasmas with the help of a new global eigenvalue code. Ions are modeled in the frame of gyrokinetic theory so that finite Larmor radius effects of these particles are retained to all orders. Non-adiabatic trapped electron dynamics is taken into account through the bounce-averaged drift kinetic equation. Assuming e...

Short wavelength temperature gradient driven modes in tokamak plasmas.

New unstable temperature gradient driven modes in an inhomogeneous tokamak plasma are identified. These modes represent temperature gradient (ion and electron) driven modes destabilized in the short wavelength regions with k( perpendicular )rho(i,e)>>1, respectively. The instability occurs due to a specific plasma response that significantly deviates from Boltzmann distribution in the regions k...

Gyrokinetic Simulations of the Nonlinear Upshift of the Critical Density Gradient for TEM Turbulence in Tokamak Fusion Plasmas

The effect of collisionality on a new nonlinear upshift of the critical density gradient for onset of Trapped Electron Mode (TEM) turbulence is investigated in detail. Both linear and nonlinear, high resolution simulations were performed on massively parallel computers using the gyrokinetic code, GS2. The TEM nonlinear upshift is analogous to the Dimits Shift for ion temperature gradient driven...

Preparative Density Gradient Centrifugations

Bull Fertility and Its Relation with Density Gradient Selected Sperm

Background sperm selection is generally used to describe methods for separation of spermatozoa for in-vitro-assisted reproduction. Few studies reported relation in vivo fertility and semen parameters after selection of fertile spermatozoa; hence, our research attempt to assess different semen parameters after post-thaw (PT) or after selecting sperm sample (SSp), using density gradient separatio...