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May 2005

Volume 12, Issue 5, Articles (05xxxx)

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Application of the low-frequency energy principle to wall modes

Bo Hu, R. Betti, and J. Manickam

Phys. Plasmas 12, 057301 (2005); http://dx.doi.org/10.1063/1.1873852 (7 pages) | Cited 36 times

Online Publication Date: 13 April 2005

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The effects of trapped particles on the stability of the n = 1 resistive wall mode are investigated by means of a generalized energy principle. The analysis is carried out for the stationary high-β plasma equilibrium of the International Thermonuclear Experimental Reactor (ITER) [ K. Tomabechi Nucl. Fusion 31, 1135 (1991) ] advanced-tokamak scenario. It is found that the trapped particle compressibility and the dissipation induced by the mode resonance with the trapped particle precession motion are stabilizing. By retaining the contribution of trapped thermal ions, electrons, and α particles, the resistive wall mode growth rate is significantly reduced and the mode almost fully suppressed. This effect vanishes for fast flowing plasmas rotating toroidally with a frequency above the ion diamagnetic frequency.
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52.35.Py Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
52.55.Tn Ideal and resistive MHD modes; kinetic modes
52.55.Fa Tokamaks, spherical tokamaks
52.55.Pi Fusion products effects (e.g., alpha-particles, etc.), fast particle effects
52.30.-q Plasma dynamics and flow
52.25.Fi Transport properties
52.40.Hf Plasma-material interactions; boundary layer effects

“Crystal” magnetic structure in axisymmetric plasma accretion disks

B. Coppi

Phys. Plasmas 12, 057302 (2005); http://dx.doi.org/10.1063/1.1883667 (8 pages) | Cited 10 times

Online Publication Date: 28 April 2005

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A general class of stationary magnetic configurations which can exist in (thin) plasma accretion disks is identified by solving analytically the coupled nonlinear equations that describe the radial and the vertical equilibrium conditions of the disk. These configurations are characterized by a “crystal” structure consisting of a sequence of toroidal current filaments that can involve null points of the poloidal magnetic field. The obtained solutions are valid in the limit where the magnetic energy density is smaller than the thermal energy density (β>1). In view of studying magnetic disk configurations from which jets can emerge, and for which the limit where β ∼ 1 is important, the relevant equilibrium equations are derived and their symmetries are pointed out.
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52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
52.25.Fi Transport properties
52.75.Xx Thermionic and filament-based sources (e.g., Q machines, double- and triple-plasma devices, etc.)

Marshall Rosenbluth and the Metropolis algorithm

J. E. Gubernatis

Phys. Plasmas 12, 057303 (2005); http://dx.doi.org/10.1063/1.1887186 (5 pages) | Cited 2 times

Online Publication Date: 28 April 2005

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The 1953 publication, “Equation of State Calculations by Very Fast Computing Machines” by N. Metropolis, A. W. Rosenbluth and M. N. Rosenbluth, and M. Teller and E. Teller [J. Chem. Phys. 21, 1087 (1953) ] marked the beginning of the use of the Monte Carlo method for solving problems in the physical sciences. The method described in this publication subsequently became known as the Metropolis algorithm, undoubtedly the most famous and most widely used Monte Carlo algorithm ever published. As none of the authors made subsequent use of the algorithm, they became unknown to the large simulation physics community that grew from this publication and their roles in its development became the subject of mystery and legend. At a conference marking the 50th anniversary of the 1953 publication, Marshall Rosenbluth gave his recollections of the algorithm’s development. The present paper describes the algorithm, reconstructs the historical context in which it was developed, and summarizes Marshall’s recollections.
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52.65.Pp Monte Carlo methods

Zonal flow dynamics and anomalous transport

Roscoe White, Liu Chen, and Fulvio Zonca

Phys. Plasmas 12, 057304 (2005); http://dx.doi.org/10.1063/1.1898225 (7 pages) | Cited 5 times

Online Publication Date: 2 May 2005

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Nonlinear equations for the slow space-time evolution of the radial drift wave-ion-temperature gradient (DW-ITG) envelope and zonal flow (ZF) amplitude have been derived within a coherent four-wave drift wave-zonal flow model. In the local limit this model demonstrates spontaneous generation of zonal flow and nonlinear drift wave-zonal flow dynamics in toroidal plasmas. The model allows slow temporal and spatial variations of the DW-ITG radial envelope, incorporating the effects of equilibrium variations, i.e., turbulence spreading and size dependence of the saturated wave intensities and transport coefficients. The competition between linear drive/damping and drift wave spreading due to linear and nonlinear group velocities and nonlinear energy transfer between DW and ZF determines the saturation levels of the fluctuating fields. The turbulence intensity level exhibits a transition from Bohm scaling at small system size (Lp/ρi) to gyro-Bohm for large system size. This system exhibits chaotic behavior and intermittency, depending on system size and proximity to marginal stability.
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52.20.Dq Particle orbits
52.65.Cc Particle orbit and trajectory

Review of progress in Fast Ignition

M. Tabak, D. S. Clark, S. P. Hatchett, M. H. Key, B. F. Lasinski, R. A. Snavely, S. C. Wilks, R. P. J. Town, R. Stephens, E. M. Campbell, R. Kodama, K. Mima, K. A. Tanaka, S. Atzeni, and R. Freeman

Phys. Plasmas 12, 057305 (2005); http://dx.doi.org/10.1063/1.1871246 (8 pages) | Cited 63 times

Online Publication Date: 5 May 2005

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Marshall Rosenbluth’s extensive contributions included seminal analysis of the physics of the laser-plasma interaction and review and advocacy of the inertial fusion program. Over the last decade he avidly followed the efforts of many scientists around the world who have studied Fast Ignition, an alternate form of inertial fusion. In this scheme, the fuel is first compressed by a conventional inertial confinement fusion driver and then ignited by a short ( ∼ 10 ps) pulse, high-power laser. Due to technological advances, such short-pulse lasers can focus power equivalent to that produced by the hydrodynamic stagnation of conventional inertial fusion capsules. This review will discuss the ignition requirements and gain curves starting from simple models and then describe how these are modified, as more detailed physics understanding is included. The critical design issues revolve around two questions: How can the compressed fuel be efficiently assembled? And how can power from the driver be delivered efficiently to the ignition region? Schemes to shorten the distance between the critical surface where the ignitor laser energy is nominally deposited and the ignition region will de discussed. The current status of Fast Ignition research is compared with our requirements for success. Future research directions will also be outlined.
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52.57.Kk Fast ignition of compressed fusion fuels
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.38.Dx Laser light absorption in plasmas (collisional, parametric, etc.)
52.25.Fi Transport properties
28.52.Cx Fueling, heating and ignition
28.52.Fa Materials
01.30.Rr Surveys and tutorial papers; resource letters
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