POP Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Feb 2013

Volume 20, Issue 2, Articles (02xxxx)

Issue Cover Spotlight Figure

Phys. Plasmas 20, 022303 (2013); http://dx.doi.org/10.1063/1.4790639 (12 pages)

Julio J. Martinell and Diego del-Castillo-Negrete
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Super-radiant backward-wave oscillators with enhanced power conversion

V. V. Rostov and A. V. Savilov

Phys. Plasmas 20, 024501 (2013); http://dx.doi.org/10.1063/1.4769028 (4 pages)

Online Publication Date: 1 February 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We propose a method for a very significant increase of the peak power of a backward-wave electron oscillator operating in the non-stationary regime of the super-radiation of short rf pulses. This method is based on sectioning: a regular self-oscillator section is supported with a section providing amplification of the super-radiant pulse. Profiling of a resonant parameter in the amplifying section is used to avoid the parasitic self-excitation and to increase the efficiency of the electron-wave interaction. In such systems, the conversion factor (the ratio between the rf pulse power and the electron beam power) can achieve a few hundred percent.
Show PACS
84.40.Fe Microwave tubes (e.g., klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.)

Quasimonoenergetic proton bunches generation from doped foil targets irradiated by intense lasers

Yun-Qian Cui, Wei-Min Wang, Zheng-Ming Sheng, Yu-Tong Li, and Jie Zhang

Phys. Plasmas 20, 024502 (2013); http://dx.doi.org/10.1063/1.4789884 (4 pages)

Online Publication Date: 4 February 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We propose a scheme to generate 10 MeV-level quasimonoenergetic proton bunches using proton-doped heavy-ion targets irradiated by intense lasers via target normal sheath acceleration. The heavy substrate ions provide a long-life quasi-stable sheath field to accelerate the doped protons at the target rear and consequently a quasimonoenergetic proton bunch is produced. The scheme is demonstrated by two-dimensional particle-in-cell simulations. An exemplificative simulation with parameters of targets made by ion-implant technique, a kind of modern doping process, gives a quasimonoenergetic bunch with peak energy ∼ 13MeV, energy spread ∼ 24%, and ∼nC charge at the focused laser intensity 1020W/cm2.
Show PACS
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.65.Rr Particle-in-cell method
52.38.Kd Laser-plasma acceleration of electrons and ions
52.38.Ph X-ray, γ-ray, and particle generation
52.40.Kh Plasma sheaths

Conservation of energy and momentum in nonrelativistic plasmas

H. Sugama, T.-H. Watanabe, and M. Nunami

Phys. Plasmas 20, 024503 (2013); http://dx.doi.org/10.1063/1.4789869 (4 pages)

Online Publication Date: 6 February 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Conservation laws of energy and momentum for nonrelativistic plasmas are derived from applying Noether's theorem to the action integral for the Vlasov-Poisson-Ampère system [Sugama, Phys. Plasmas 7, 466 (2000)]. The symmetric pressure tensor is obtained from modifying the asymmetric canonical pressure tensor with using the rotational symmetry of the action integral. Differences between the resultant conservation laws and those for the Vlasov-Maxwell system including the Maxwell displacement current are clarified. These results provide a useful basis for gyrokinetic conservation laws because gyrokinetic equations are derived as an approximation of the Vlasov-Poisson-Ampère system.
Show PACS
52.25.Dg Plasma kinetic equations
52.35.Bj Magnetohydrodynamic waves (e.g., Alfven waves)
02.30.Jr Partial differential equations
02.60.Gf Algorithms for functional approximation

Quick asymptotic expansion aided by a variational principle

Eliezer Hameiri

Phys. Plasmas 20, 024504 (2013); http://dx.doi.org/10.1063/1.4789987 (4 pages)

Online Publication Date: 6 February 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is shown how expanding asymptotically a variational functional can yield the asymptotic expansion of its Euler equation. The procedure is simple but novel and requires taking the variation of the expanded functional with respect to the leading order of the originally unknown function, even though the leading order of this function has already been determined in a previous order. An example is worked out that of a large aspect ratio tokamak plasma equilibrium state with relatively strong flows and high plasma beta.
Show PACS
52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
52.55.Fa Tokamaks, spherical tokamaks
02.30.Lt Sequences, series, and summability
02.30.Xx Calculus of variations

On Lyapunov boundary control of unstable magnetohydrodynamic plasmas

H. Tasso and G. N. Throumoulopoulos

Phys. Plasmas 20, 024505 (2013); http://dx.doi.org/10.1063/1.4791656 (3 pages)

Online Publication Date: 13 February 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Starting from a simple, marginally stable model considered for Lyapunov based boundary control of flexible mechanical systems, we add a term driving an instability and prove that for an appropriate control condition the system can become Lyapunov stable. A similar approximate extension is found for the general energy principle of linearized magnetohydrodynamics. The implementation of such external instantaneous actions may, however, impose challenging constraints for fusion plasmas.
Show PACS
52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
52.35.Py Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
52.65.-y Plasma simulation
02.30.Yy Control theory
02.60.Gf Algorithms for functional approximation

Experimental observation of the behaviour of cogenerated dusty plasma using a bipolar pulsed direct current power supply

Sanjib Sarkar, M. Bose, J. Pramanik, and S. Mukherjee

Phys. Plasmas 20, 024506 (2013); http://dx.doi.org/10.1063/1.4792154 (4 pages)

Online Publication Date: 13 February 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have experimentally observed the behaviour of cogenerated dusts in unmagnetized plasma produced using a bipolar pulsed dc power supply. In this experiment, the dust particles have been generated through sputtering of graphite cathode and were stratified between two electrodes. This stratification of dust clouds has obtained at a typical range of plasma parameters, namely, 650 V (peak-to-peak) with 0.2 mbar pressure. In above condition, we detected the Taylor-like instability at the interface of two dusty clouds with different densities. A very less dust density (void like) region inside the lesser dust density portion is also noted. Again, it has been observed that a self excited dust density wave propagates towards the higher density dust fluid inside the system as well as a stationary band structure of thin multiple layers of dust particles when we apply a higher voltage (750 V peak-to-peak). The wavelength, phase velocity, and frequency of the excited wave have also been estimated.
Show PACS
52.27.Lw Dusty or complex plasmas; plasma crystals
52.35.Py Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
52.50.Dg Plasma sources
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close