Neoclassical Toroidal Viscosity Calculations in Tokamaks Using a δf Monte Carlo Simulation and Their Verifications

Neoclassical toroidal viscosities (NTVs) in tokamaks are investigated using a δf Monte Carlo simulation, and are successfully verified with a combined analytic theory over a wide range of collisionality. A Monte Carlo simulation has been required in the study of NTV since the complexities in guiding-center orbits of particles and their collisions cannot be fully investigated by any means of analytic theories alone. Results yielded the details of the complex NTV dependency on particle precessions and collisions, which were predicted roughly in a combined analytic theory. Both numerical and analytic methods can be utilized and extended based on these successful verifications

Gyrokinetic turbulent transport simulation of a high ion temperature plasma in large helical device experiment

Ion temperature gradient turbulent transport in the large helical device (LHD) is investigated by means of gyrokinetic simulations in comparison with the experimental density fluctuation measurements of ion-scale turbulence. The local gyrokinetic Vlasov simulations are carried out incorporating full geometrical effects of the LHD configuration, and reproduce the turbulent transport levels comparable to the experimental results. Reasonable agreements are also found in the poloidal wavenumber spectra of the density fluctuations obtained from the simulation and the experiment. Numerical analysis of the spectra of the turbulent potential fluctuations on the two-dimensional wavenumber space perpendicular to the magnetic field clarifies the spectral transfer into a high radial wavenumber region which correlates with the regulation of the turbulent transport due to the zonal flows. The resultant transport levels at different flux surfaces are expressed in terms of a simple linear relation between the transport coefficient and the ratio of the squared turbulent potential fluctuation to the averaged zonal flow amplitude

Metamorphosis of plasma turbulence-shear flow dynamics through a transcritical bifurcation

The structural properties of an economical model for a confined plasma turbulence governor are investigated through bifurcation and stability analyses. A close relationship is demonstrated between the underlying bifurcation framework of the model and typical behavior associated with low- to high-confinement transitions such as shear flow stabilization of turbulence and oscillatory collective action. In particular, the analysis evinces two types of discontinuous transition that are qualitatively distinct. One involves classical hysteresis, governed by viscous dissipation. The other is intrinsically oscillatory and non-hysteretic, and thus provides a model for the so-called dithering transitions that are frequently observed. This metamorphosis, or transformation, of the system dynamics is an important late side-effect of symmetry-breaking, which manifests as an unusual non-symmetric transcritical bifurcation induced by a significant shear flow drive.Comment: 17 pages, revtex text, 9 figures comprised of 16 postscript files. Submitted to Phys. Rev.

Evaluasi Kesesuaian Lahan Kualitatif dan Kuantitatif Pertanaman Padi Sawah (Oryza Sativa L.) di Kelurahan Tejosari Kecamatan Metro Timur Kota Metro

Kebutuhan pangan dalam negeri semakin meningkat seiring dengan jumlah penduduk Indonesia yang terus bertambah, sehingga untuk mencukupi kebutuhan tersebut merupakan masalah yang cukup serius.Konsumsi beras yang tinggi tidak didukung dengan produksi padi di dalam negeri, maka suatu jenis tanaman harus ditanam pada tempat yang sesuai dengan persyaratan tumbuhnya. Untuk itu diperlukan pengetahuan mengenai evaluasi lahan baik secara fisik (kualitatif) maupun ekonomi (kuantitatif). Penelitian dilaksanakan pada lahan pertanaman Padi Sawah irigasi (Oryza Sativa L.) milik 6 kelompok tani di Kelurahan Tejosari Kecamatan Metro Timur Kota Metro dengan luas areal 237 ha pada bulan November 2014. Analisis tanah dilakukan di Laboratorium Ilmu Tanah Fakultas Pertanian Universitas Lampung. Evaluasi kesesuaian lahan kualitatif dilakukan berdasarkan persyaratan tumbuh tanaman Padi sawah irigasi menurut kriteria Djaenudin, dkk (2003), dan evaluasi kesesuaian lahan kuantitatif dilakukan dengan menganalisis kelayakan finansial melalui perhitungan NPV, Net B/C, dan IRR. Hasil penelitian menunjukkan bahwa lahan pertanaman padi sawah irigasi di Kelurahan Tejosari Kecamatan Metro Timur berdasarkan kondisi fisik lingkungan menurut Djaenudin, dkk. (2003), termasuk ke dalam kelas kesesuaian lahan sesuai marjinal dengan faktor pembatas Kejenuhan Basa dan C-organik (S3nr), dan secara finansial layak untuk dilanjutkan dengan nilai NPV sebesar Rp 41.383.725per ha, Net B/C sebesar 3,62, dan IRR sebesar 31,46.% per tahun