| 1. |
|
|
| 2. |
- Anderson, Johan, 1973, et al.
(författare)
-
A comparison of drift wave stability in stellarator and tokamak geometry
- 2002
-
Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 9:5, s. 1629-
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of plasma geometry on the linear stability of electrostatic ion-temperature-gradient driven drift modes (ITG modes) is investigated. An advanced fluid model is used for the ions together with Boltzmann distributed electrons. The derived eigenvalue equation is solved numerically. A comparison is made between an H – 1NF [Fusion Technol. 17, 123 (1990)] like stellarator equilibrium, a numerical tokamak equilibrium and the analytical s - alpha equilibrium. The numerical and the analytical tokamak are found to be in good agreement in the low inverse aspect ratio limit. The growth rates of the tokamak and stellarator are comparable whereas the modulus of the real frequency is substantially larger in the stellarator. The threshold in Ln/LT for the stellarator is found to be somewhat larger. In addition, a stronger stabilization of the ITG mode growth is found for large L n / R in the stellarator case.
|
|
| 3. |
- Anderson, Johan, 1973, et al.
(författare)
-
Non-Linear Langevin and Fractional Fokker-Planck Equations for Anomalous Diffusion by Levy Stable~Processes
- 2018
-
Ingår i: Entropy. - : MDPI AG. - 1099-4300. ; 20:10
-
Tidskriftsartikel (refereegranskat)abstract
- The~numerical solutions to a non-linear Fractional Fokker--Planck (FFP) equation are studied estimating the generalized diffusion coefficients. The~aim is to model anomalous diffusion using an FFP description with fractional velocity derivatives and Langevin dynamics where L\'{e}vy fluctuations are introduced to model the effect of non-local transport due to fractional diffusion in velocity space. Distribution functions are found using numerical means for varying degrees of fractionality of the stable L\'{e}vy distribution as solutions to the FFP equation. The~statistical properties of the distribution functions are assessed by a generalized normalized expectation measure and entropy and modified transport coefficient. The~transport coefficient significantly increases with decreasing fractality which is corroborated by analysis of experimental data.
|
|
| 4. |
- Aziz, Maria, et al.
(författare)
-
Efficient Removal of Lead and Chromium From Aqueous Media Using Selenium Based Nanocomposite Supported by Orange Peel
- 2022
-
Ingår i: Frontiers in Environmental Science. - : Frontiers Media S.A.. - 2296-665X. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- This study presents the synthesis of activated orange peel, derived from bio-waste (orange peel) and its doping with selenium nano-particles to enhance the adsorption capacity. The synthesized nanocomposite orange peel/Selenium (OP/Se) was applied as adsorbents for the removal of Lead (Pb) and Chromium (Cr) from synthetic waste water as an economical water cleaning technology. Orange peel/Selenium nanocomposite was characterized by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscopy (SEM). Scanning electron microscopy results showed the porous structure of OP/Se nanocomposite and distinct peaks observed in XRD and FTIR spectra depicted the successful synthesis of nanocomposite. Batch experiments were conducted to figure out the effect of different parameters on adsorption of Pb and Cr by using Atomic Absorption Spectroscopy. The maximum adsorption capacity of 99.9% was achieved for both lead and chromium at acidic pH. While at temperature of 60°C the maximum adsorption of 98.3 and 95.9% was found for Pb and Cr respectively. Furthermore the experimental data was examined with Pseudo-first order, first-order and Pseudo-second order kinetic model, as well as Morris Intraparticle diffusion model where the pseudo second order was best fitted which indicated the chemisorption mechanism in adsorption process. The adsorption process followed the Langmuir isotherm model verified that OP/Se nanocomposite was found to be favorable for the process of adsorption. The adsorption thermodynamics indicate that adsorption of heavy metals ions is spontaneous (ΔG° < 0) and the adsorption increases with increase in temperature which means that reaction was endothermic in nature. This study revealed that the synthesized bio-activated nanocomposite was an efficient adsorbent material for the removal of heavy metals from waste water.
|
|
| 5. |
- Mahmood, Ansar, 1975, et al.
(författare)
-
Collisionless trapped electron and ion temperature gradient modes in an advanced tokamak equilibrium
- 2009
-
Ingår i: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 16:2, s. 022503-
-
Tidskriftsartikel (refereegranskat)abstract
- The linear stability of coupled collisionless trapped electron (TE) and ion temperature gradient (ITG) modes is investigated in an International Thermonuclear Experimental Reactor [C. Gormezano , Nucl. Fusion 47, S285 (2007)]-like magnetic field configuration. An advanced fluid model in the electrostatic limit and the ballooning mode formalism are used to derive an eigenvalue equation. The growth rates and real frequencies of the most unstable modes and their eigenfunctions are calculated. The coexistence of unstable ITG and TE modes and their relative strengths with respect to the fraction of trapped electrons, wave vector, and local plasma parameters, such as density gradient, electron/ion temperature gradient, and ion to electron temperature ratio are analyzed. The influence of geometrical factors, such as local/global magnetic shear and magnetic field curvature on both ITG and TE modes is also discussed.
|
|
| 6. |
- Mahmood, Ansar, 1975, et al.
(författare)
-
Drift waves in an ITER-like geometry
- 2007
-
Ingår i: First ITER Summer School: Turbulent Transport in Fusion Plasmas, Aix en Provence (France), 15-20 July 2007..
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Mahmood, Ansar, 1975, et al.
(författare)
-
Study of collisionless TE and ITG modes in an ITER-like equilibrium
- 2008
-
Ingår i: Proceedings of the 35th EPS Conference on Plasma Physics, Hersonissos, Greece, 9-13 June, 2008, ECA. - 9781622763351 ; 32F:2, s. 4.024-
-
Konferensbidrag (refereegranskat)abstract
- The linear stability of collisionless trapped electron (TE) and ion temperature gradient (ITG) modes is studied in an ITER-like magnetic field configuration. An advanced fluid model for ITG-TE mode [1] is used and an eigenvalue equation along a field line is derived using the ballooning mode formalism. The eigenvalue problem is solved numerically using a standard shooting technique and applying WKB type boundary conditions. The growth rates and real frequencies of the most unstable modes and their eigenfunctions are calculated. Effects of the magnetic shear, trapped electrons fraction, wavevector, temperature ratios, and temperature gradients on mode stability are discussed.
|
|
| 10. |
- Mahmood, Ansar, 1975, et al.
(författare)
-
Study of ITG Modes in ITER geometry
- 2004
-
Ingår i: Annual meeting RUSA, April 20-21, Nyköping , (2004).
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
