Properties of freely decaying and driven turbulence of fusion plasmas using gyrokinetic particle simulation
In a recent work, the effects of nonlinear self-consistent profile relaxation on the ITG turbulence in global delta-f particle simulations were studied [1] using Gyrokinetic Toroidal Code (GTC) [2]. In contrast to several other gyrokinetic turbulence models, GTC shows that the turbulence is insensitive to minute or drastic profile changes and reaches the similar flux levels irrespective of whether or not it is a driven or freely decaying turbulence. In the present work, we address the spectral properties of gyrokinetic turbulence and argue that correct inclusion of parallel velocity space nonlinearity may bring forth certain important late-time features such as Geodesic Acoustic Modes like (GAM) structures.
A Fourier-Hermite Study of Dissipation in 1+1-D Models of Fusion Plasmas
This study investigates dissipation in fusion plasmas confined by strong magnetic fields, as described by 5-D gyrokinetic theory. We first derive a reduced model for the dynamics parallel to the magnetic field in both physical and velocity spaces. This model closely resembles the classic one-dimensional Vlasov-Poisson system, but replaces Poisson’s law with the quasineutrality condition relevant to multi-species fusion plasmas. We construct a numerical model using a truncated Fourier-Hermite representation, validate it against existing results for the Vlasov-Poisson system, and then apply it to fusion plasmas. Similarities and differences between the classic and fusion cases are assessed. We then investigate the effect of unsteady forcing by a neutral particle beam, representing both an actual tokamak energy source and a model for turbulence in the omitted dimensions perpendicular to the magnetic field. We find that even small amplitude forcing may substantially affect the long-time behavior, which may have important consequences in the design of efficient fusion reactors.
Novel polymeric hydrogel composites: Synthesis, physicochemical, mechanical and biocompatible properties
In this research study, novel hydrogel composite films were constructed using different ratios of poly (vinyl alcohol) (PVA)/kappa-carrageenan (KC) (PVA90/KC10%, PVA80/KC20%, PVA70/KC30%, PVA60/KC40%) crosslinked with glutaraldehyde (0.025%) and investigated their physicochemical characteristics such as mechanical, thermal, morphological, swelling behaviour, and cell viability. SEM and FTIR revealed that surface morphology changed to heterogeneous and the presence of molecular interaction among the polymers. PVA90KC10 and PVA60KC40 exhibited smaller and larger pores on surface respectively. The change in the proportion of PVA and KC also triggered the tensile strength (Ts) of the film and the highest Ts observed were 21.60 MPa for PVA60KC40. Moreover, the thermal analysis showed three-phase degradation, and an increase in KC40 concentration results inversely proportional to a decrease in the rate of thermal degradation. Further, swelling and in-vitro biodegradation study confirmed the enhanced perseverance of water uptake for PVA60KC40 (286%) due to pores structure of the hydrogel film and PVA and KC alone degraded faster as compare to other films results suggested higher concentration of PVA90KC10 showed lower degradation rate and highest for PVA60KC40 about 6% and 22% respectively. Further, the cell viability was studied with MTT assay method by using NIH3T3 and HEK-293 cells for biocompatibility study revealed NIH3T3 cells were more biocompatible than HEK-293 and cell viability percent for PVA60KC40 showed the highest cell attachment about 99%. Overall corroborating data obtained from the study attested to the average swelling, appreciable mechanical characters, good interaction between molecules, and cell viability of the constructed PVA/KC hydrogel film, these all characters pave to be used as a potential template for biomedical applications such as tissue engineering and drug delivery.