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Physics of Plasmas Collection (47 Books)


 
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Physics of Plasmas : Role of secondary long wavelength structures ...

By: Jiquan Li and Y. Kishimoto

Description: The dynamics of secondary long wavelength structures (LWSs) in electron temperature gradient (ETG) driven turbulence are investigated by performing gyrofluid simulations and modeling analyses in a slab geometry with an emphasis of the underlying nonlinear interaction processes. It is shown that the back-reaction of the secondary LWS on the ambient fluctuations essentially contributes to saturating ETG instability and limiting the electron transport. The LWS ...

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Physics of Plasmas : Pitch angle scattering and synchrotron radiat...

By: J. R. Martín-Solís and R. Sánchez

Description: In a recent work [ J. R. Martín-Solís and R. Sánchez, Phys. Plasmas 13, 012508 (2006) ], the increase that the presence of stochastic magnetic fields causes on the synchrotron radiation losses of relativistic runaway electrons was quantified using a guiding-center approximation. Here, we complete those studies by considering instead the mechanism which dominates the interaction at the gyromotion level. It is shown that, under typical tokamak conditions, the ...

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Physics of Plasmas : Toroidal equilibria in spherical coordinates

By: K. H. Tsui

Description: The standard Grad–Shafranov equation for axisymmetric toroidal plasma equilibrium is customary expressed in cylindrical coordinates with toroidal contours, and through which benchmark equilibria are solved. An alternative approach to cast the Grad–Shafranov equation in spherical coordinates is presented. This equation, in spherical coordinates, is examined for toroidal solutions to describe low β Solovev and high β plasma equilibria in terms of elementary functions.

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Physics of Plasmas : Cross-point coronal plasma dynamics in two- a...

By: R. E. Madden, S. C. Bott, D. Haas, Y. Eshaq, U. Ueda et al

Description: Studies of the late time diode gap formation in two- and four-wire tungsten x-pinches using an 80 kA, 50 ns current pulse are presented. Quantitative measurements of the coronal plasma density are recovered using interferometry simultaneously with laser shadowgraphy. Axial expansion of the gap occurs at ∼ 106 cm/s for both two- and four-wire systems and is likely to be driven by an axial J×B force resulting from radial current flow in the plasma minidiode “e...

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Physics of Plasmas : Simulations of electron transport and ignitio...

By: A. A. Solodov, K. S. Anderson, R. Betti, V. Gotcheva, J. Myatt et al

Description: The performance of high-gain, fast-ignition fusion targets is investigated using one-dimensional hydrodynamic simulations of implosion and two-dimensional (2D) hybrid fluid-particle simulations of hot-electron transport, ignition, and burn. The 2D/3D hybrid-particle-in-cell code LSP [ D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001) ] and the 2D fluid code DRACO [ P. B. Radha et al., Phys. Plasmas 12, 056307 (2005) ] are integrated to ...

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Physics of Plasmas : Characterization of converging shock waves ge...

By: S. Efimov, A. Fedotov, S. Gleizer, V. Tz. Gurovich, G. Bazalitski et al

Description: Results of ∼ 200 kbar pressure generation at 50 μm distance from the implosion axis of the converging shock wave produced by an underwater electrical explosion of a cylindrical wire array are reported. The array was exploded using a submicrosecond high-current generator (stored energy of ∼ 4.2 kJ, current amplitude of ∼ 325 kA, rise time of ∼ 1 μs). Multiframe shadow imaging of the shock wave was used to determine its time of flight. These data were applied ...

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Physics of Plasmas : High intensity x-ray line emission from alumi...

By: Jiamin Yang, Zhimin Hu, Jiyan Zhang, Tuo Zhu, Yang Zhao et al

Description: The K-shell x-ray spectra from the aluminum plasmas generated by the interaction of the 120 TW, 30 fs laser with aluminum targets have been measured by defocusing the laser beam. Laser energy-normalized intensity of the He-a line increases with the laser intensity approximately as a power law ε∝ILγ with the much smaller exponent of γ = 0.062 compared to γ = 0.2 ∼ 0.5 in the previous experiments, which is caused by the stronger radial thermal diffusivity in t...

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Physics of Plasmas : Stability of three-dimensional electron holes

By: M. Berthomier, G. Dubois, and L. Muschietti

Description: A self-consistent kinetic model of three-dimensional (3D) electron holes in a strongly magnetized collisionless plasma is presented. A stability study of these localized electrostatic structures has been carried out. The analysis of the motion of trapped particles in the 3D potential structure suggests using the Hamiltonian approach to describe how electron holes interact with an external electrostatic perturbation. Using 3D action-angle variables and pertur...

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Physics of Plasmas : Physics of collisionless phase mixing

By: D. Tsiklauri and T. Haruki

Description: Previous studies of phase mixing of ion cyclotron (IC), Alfvénic, waves in the collisionless regime have established the generation of parallel electric field and hence acceleration of electrons in the regions of transverse density inhomogeneity. However, outstanding issues were left open. Here we use the 2.5 D, relativistic, fully electromagnetic particle-in-cell code and an analytic magnetohydrodynamic (MHD) formulation, to establish the following points: ...

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Physics of Plasmas : A new fast reconnection model in a collisionl...

By: David Tsiklauri

Description: Based on the first principles [i.e., (i) by balancing the magnetic field advection with the term containing electron pressure tensor nongyrotropic components in the generalized Ohm’s law; (ii) using the conservation of mass; and (iii) assuming that the weak magnetic field region width, where electron meandering motion supports electron pressure tensor off-diagonal (nongyrotropic) components, is of the order of electron Larmor radius] a simple model of magnet...

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Physics of Plasmas : Instability of wave modes in a free-electron ...

By: T. Mohsenpour and B. Maraghechi

Description: The dispersion relation for a free-electron laser (FEL) with a one-dimensional helical wiggler and an ion channel, in the collective regime, is found with all relativistic effects on the space-charge wave and radiation included. This dispersion relation is solved numerically to study the unstable interaction among all wave modes. In group I orbits, coupling between the positive-energy space-charge wave and the left circularly polarized electromagnetic wave i...

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Physics of Plasmas : Simulation of quasimonoenergetic electron bea...

By: X. Davoine, E. Lefebvre, J. Faure, C. Rechatin, A. Lifschitz et al

Description: The collision of two laser pulses can inject electrons into a wakefield accelerator, and has been found to produce stable and tunable quasimonoenergetic electron beams [ J. Faure et al., Nature 444, 737 (2006) ]. This colliding pulse scheme is studied here with 3D particle-in-cell simulations. The results are successfully compared with experimental data, showing the accuracy of the simulations. The involved mechanisms (laser propagation, wake inhibition, ele...

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Physics of Plasmas : Laser mode effects on the ion acceleration du...

By: M. Chen, A. Pukhov, Z. M. Sheng, and X. Q. Yan

Description: Ion acceleration by circularly polarized laser pulses interacting with foil targets is studied using two dimensional particle-in-cell simulations. It is shown that laser pulses with transverse super-Gaussian profile help in avoiding target deformation as compared with the usual Gaussian pulse. This improves monochromaticity of the accelerated ion spectrum. Two kinds of surface instabilities have been found during the interaction. These instabilities can pote...

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Physics of Plasmas : Demonstration of detuning and wavebreaking ef...

By: N. A. Yampolsky, N. J. Fisch, V. M. Malkin, E. J. Valeo, R. Lindberg et al

Description: A plasma-based resonant backward Raman amplifier/compressor for high power amplification of short laser pulses might, under ideal conditions, convert as much as 90% of the pump energy to the seed pulse. While the theoretical highest possible efficiency of this scheme has not yet been achieved, larger efficiencies than ever before obtained experimentally (6.4%) are now being reported, and these efficiencies are accompanied by strong pulse compression. Based o...

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Physics of Plasmas : Gamma ray sources using imperfect relativisti...

By: J. T. Mendonça and A. Serbeto

Description: The collective backscattering of intense laser radiation by energetic electron beams is considered. Exact solutions for the radiation field are obtained, for arbitrary electron pulse shapes and laser intensities. The electron beams act as imperfect nonlinear mirrors on the incident laser radiation. This collective backscattering process can lead to the development of new sources of ultrashort pulse radiation in the gamma-ray domain. Numerical examples show t...

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Physics of Plasmas : Doppler spectroscopy of hydrogen Balmer lines...

By: N. M. Šišovic and N. Konjevic

Description: The results of Doppler spectroscopy of hydrogen Balmer lines from a stainless steel (SS) and copper (Cu) hollow cathode (HC) glow discharge in ammonia and argon-ammonia mixture are reported. The experimental profiles in ammonia discharge are fitted well by superposing three Gaussian profiles. The half widths, in energy units, of narrow and medium Gaussians are in the ranges 0.3–0.4 eV and 3–4 eV, respectively, for both hollow cathodes what is expected on the...

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Physics of Plasmas : Modeling of an advanced concept of a double s...

By: L. Garrigues, C. Boniface, G. J. Hagelaar, and J. P. Boeuf

Description: We present a study of the principle and operation of a two-stage Hall effect thruster, the SPT-MAG, using a two-dimensional quasineutral hybrid model coupled with a Monte Carlo simulation of electron transport. The purpose of the two-stage design is the separation of ion production and acceleration in two separate chambers, the ionization stage and the acceleration stage, with separate control of acceleration voltage and total ionization. The originality of ...

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Physics of Plasmas : Stabilizing of low frequency oscillation in H...

By: Daren Yu, Chunsheng Wang, Liqiu Wei, Chao Gao, and Guang Yu

Description: Numerical simulations and experiments have been conducted to investigate the effects of a filter on low frequency oscillation in Hall thrusters. With one-dimensional quasineutral hydrodynamic model, the effects of filter components are studied by way of simulation computations. The simulation results show that with proper filter parameters, low frequency oscillation can be stabilized. Further, an eigenvalue study of the linear stability has been performed an...

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Physics of Plasmas : Spectroscopic study on rotational and vibrati...

By: Xiao-Jiang Huang, Yu Xin, Lei Yang, Quan-Hua Yuan, and Zhao-Yuan Ning

Description: By using optical emission spectroscopy, the vibrational and rotational temperatures of N2 and N2+ in capacitively coupled plasma (CCP) discharges driven by dual-frequency 41 MHz and 2 MHz are investigated. The vibrational and rotational temperatures are measured based on the N2+ first negative system and N2 second positive system overlapped molecular emission optical spectrum, using the method of comparing the measured and calculated spectra with a least-squ...

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Physics of Plasmas : Electrostatic solitary waves in a magnetized ...

By: S. K. Maharaj, R. Bharuthram, S. V. Singh, S. R. Pillay, and G. S. Lakhina

Description: The nonlinear evolution of driven low-frequency electrostatic waves is investigated in a three-component magnetized dusty plasma comprised of a warm dust fluid, electrons, and ions. Electrons as well as ions are considered to have Boltzmann distributions. The fluid equations for the dust along with the quasineutrality condition are used to obtain a single nonlinear differential equation for the electric field. Periodic solutions of the nonlinear differential...

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