In the present study, three types of coloured fibre cottons, i.e. white, brown and green, were compared for their fibre quality and yield. The comparison of fibre quality suggested that coloured fibre cotton was inferior as compared with white fibre cotton. To understand the effect of cellulose, mineral elements [nitrogen (N), phosphorus (P) and potassium (K)] and pH of fibre cells on the quality of fibre, these components were studied at different fibre cell developed stages in all three fibre cotton types. The cellulose content is closely associated with the quality of fibre. The higher fibre quality of white fibre cotton might be the result of the high cellulose content in it compared with coloured fibre cotton. A rapid and slow decrease in pH in white and coloured cottons, respectively, might have some effects on fibre elongation. Among the mineral contents, potassium is positively correlated with the fibre quality traits. The pigment development patterns in brown and green fibre cottons are not similar. In green fibre cotton it takes more time to deepen in colour as compared with brown fibre cotton. Possible strategies for the improvement in quality of coloured fibre cotton are discussed. The results of heterosis studies in coloured fibre cotton suggest that heterosis could improve yield and quality of coloured fibre cotton. In the present study, the hybrids between ZJU12A x ZJU05R and ZJU18A x ZJU01R, having an acceptable lint colour types plus better fibre quality and high yield performance, may be exploited further for their heterotic advantages.

To help reveal the complete picture of linear kinetic drift modes, four independent numerical approaches, based on integral equation, Euler initial value simulation, Euler matrix eigenvalue solution and Lagrangian particle simulation, respectively, are used to solve the linear gyrokinetic electrostatic drift modes equation in Z-pinch with slab simplification and in tokamak with ballooning space coordinate. We identify that these approaches can yield the same solution with the difference smaller than 1%, and the discrepancies mainly come from the numerical convergence, which is the first detailed benchmark of four independent numerical approaches for gyrokinetic linear drift modes. Using these approaches, we find that the entropy mode and interchange mode are on the same branch in Z-pinch, and the entropy mode can have both electron and ion branches. And, at strong gradient, more than one eigenstate of the ion temperature gradient mode (ITG) can be unstable and the most unstable one can be on non-ground eigenstates. The propagation of ITGs from ion to electron diamagnetic direction at strong gradient is also observed, which implies that the propagation direction is not a decisive criterion for the experimental diagnosis of turbulent mode at the edge plasmas.

We report the first experimental evidence of Alfvénic ion temperature gradient (AITG) modes in HL-2A Ohmic plasmas. A group of oscillations with f = 15 − 40 kHz and n = 3 − 6 is detected by various diagnostics in high-density Ohmic regimes. They appear in the plasmas with peaked density profiles and weak magnetic shear, which indicates that corresponding instabilities are excited by pressure gradients. The time trace of the fluctuation spectrogram can be either a frequency staircase, with different modes excited at different times or multiple modes may simultaneously coexist. Theoretical analyses by the extended generalized fishbone-like dispersion relation (GFLDR-E) reveal that mode frequencies scale with ion diamagnetic drift frequency and ηi, and they lie in KBM-AITG-BAE frequency ranges. AITG modes are most unstable when the magnetic shear is small in low pressure gradient regions. Numerical solutions of the AITG/KBM equation also illuminate why AITG modes can be unstable for weak shear and low pressure gradients. It is worth emphasizing that these instabilities may be linked to the internal transport barrier (ITB) and H-mode pedestal physics for weak magnetic shear. Kinetic Alfvén and pressure gradient driven instabilities are very common in magnetized plasmas both in space and laboratory[1][2][3]. In present-day fusion and future burning plasmas, they are easily excited by energetic particles (EPs) and/or pressure gradients. They can not only cause the loss and redistribution of EPs but also affect plasma confinement and transport[4][5]. The physics associated with them is an intriguing but complex area of research. For weak magnetic shear (s = (r/q)(dq/dr) ∼ 0) and low pressure gradients (α = −R 0 q 2 dβ/dr < 1; with β the ratio of kinetic to magnetic pressures.), the stability and effect of them, such as Alfvénic ion temperature gradient (AITG) mode[6][7]/kinetic ballooning mode (KBM)[8], have not been hitherto unrecognized. At weak magnetic shear, the first pressure gradient threshold becomes very small or vanishes and the AITG/KBM spectrum is unstable in the very low pressure gradient region[9][10]. For equilibria with reverse shear where q min is off axis and α max near q min , there exists an unstable low-n global branch of AITG and trapped electron dynamics can further destabilize it[11].The AITG/KBM modes, on the one hand, can cause cross-field plasma transport that set an upper limit on the arXiv:1611.05538v1 [physics.plasm-ph]

No abstract

Wavy-structured two-dimensional (2D) photonic crystal (PC) is possessed of isofrequency contours of rectangular form and is therefore capable of self-collimation. The self-guiding phenomenon is studied by calculating the intensity of the electromagnetic waves through slabs of the PC. Superlensing based on self-collimation of wavy-structured 2DPC is also investigated by analyzing the field pattern where point source is used. The full width at half maximum of image point is calculated to be 0.28λ. The position of the image is always located in the near-field domain of the slab. Image quality degrades gradually as the slab thickness or the source-slab distance increases.