952 research outputs found
Perpendicular momentum injection by lower hybrid wave in a tokamak
The injection of lower hybrid waves for current drive into a tokamak affects
the profile of intrinsic rotation. In this article, the momentum deposition by
the lower hybrid wave on the electrons is studied. Due to the increase in the
poloidal momentum of the wave as it propagates into the tokamak, the parallel
momentum of the wave increases considerably. The change of the perpendicular
momentum of the wave is such that the toroidal angular momentum of the wave is
conserved. If the perpendicular momentum transfer via electron Landau damping
is ignored, the transfer of the toroidal angular momentum to the plasma will be
larger than the injected toroidal angular momentum. A proper quasilinear
treatment proves that both perpendicular and parallel momentum are transferred
to the electrons. The toroidal angular momentum of the electrons is then
transferred to the ions via different mechanisms for the parallel and
perpendicular momentum. The perpendicular momentum is transferred to ions
through an outward radial electron pinch, while the parallel momentum is
transferred through collisions.Comment: 22 pages, 4 figure
Analysis of the heating scenarios of the ion Bernstein wave (IBW) experiment in Frascati Tokamak Upgrade
Behavioral Priming: It's All in the Mind, but Whose Mind?
The perspective that behavior is often driven by unconscious determinants has become widespread in social psychology. Bargh, Chen, and Burrows' (1996) famous study, in which participants unwittingly exposed to the stereotype of age walked slower when exiting the laboratory, was instrumental in defining this perspective. Here, we present two experiments aimed at replicating the original study. Despite the use of automated timing methods and a larger sample, our first experiment failed to show priming. Our second experiment was aimed at manipulating the beliefs of the experimenters: Half were led to think that participants would walk slower when primed congruently, and the other half was led to expect the opposite. Strikingly, we obtained a walking speed effect, but only when experimenters believed participants would indeed walk slower. This suggests that both priming and experimenters' expectations are instrumental in explaining the walking speed effect. Further, debriefing was suggestive of awareness of the primes. We conclude that unconscious behavioral priming is real, while real, involves mechanisms different from those typically assumed to cause the effect
A Study of the Radiative Ke3 Decay and Search for Direct Photon Emission with the KLOE Detector
We present a measurement of the ratio R =
\Gamma(\keg;\Estar>30\mev,\qstar>20^\circ)\Gamma(\kegf) of data corresponding to about 3.5
million Ke3(g) events and about 9000 radiative events. Our result is R=(924 +/-
23(stat) +/-16(syst)10^{-5} for the branching ratio and X=-2.3 +/- 1.3(stat)
+/- 1.4(syst) for the parameter describing direct emission.Comment: 8 pages, 7 figure
Determination of Dalitz plot slopes and asymmetries with the KLOE detector
We have studied, with the KLOE detector at the DANE -Factory, the
dynamics of the decay using mesons from the
decay for an integrated luminosity = 450
pb. From a fit to the Dalitz plot density distribution we obtain a
precise measurement of the slope parameters. An alternative parametrization
relates the slopes to that for showing the
consistency of KLOE results for both channels. We also obtain the best
confirmation of the -invariance in the decay.Comment: 15 pages, 7 figure
Vus and lepton universality from kaon decays with the KLOE detector
KLOE has measured most decay branching ratios of Ks, Kl and K+/- mesons. It
has also measured the Kl and the K+- lifetime and determined the shape of the
form factors involved in kaon semileptonic decays. We present in the following
a description of the above measurements and a well organized compendium of all
of our data, with particular attention to correlations. These data provide the
basis for the determination of the CKM parameter Vus and a test of the
unitarity of the quark flavor mixing matrix. We also test lepton universality
and place bounds on new physics using measurements of Vus from Kl2 and Kl3
decays.Comment: 23 pages, 12 figures. Submitted to JHE
Particle simulation of lower hybrid wave propagation in fusion plasmas
Global particle simulations of the lower hybrid (LH) waves have been carried out using fully kinetic ions and drift kinetic electrons with a realistic electron-to-ion mass ratio. The LH wave frequency, mode structure, and electron Landau damping from the electrostatic simulations agree very well with the analytic theory. Linear simulation of the propagation of a LH wave-packet in the toroidal geometry shows that the wave propagates faster in the high field side than the low field side, in agreement with a ray tracing calculation. This poloidal asymmetry arises from the non-conservation of the poloidal mode number due to the non-uniform magnetic field. In contrast, the poloidal mode number is conserved in the cylindrical geometry with the uniform magnetic field.Physics, Fluids & PlasmasPhysics, NuclearSCI(E)[email protected]
Heating, current drive and energetic particle studies on JET in preparation of ITER operation
This paper summarizes the recent work on JET in the three areas of heating, current drive and energetic particles. The achievements have extended the possibilities of JET, have a direct connection to ITER operation and provide new and interesting physics. Toroidal rotation profiles of plasmas heated far off axis with little or no refuelling or momentum input are hollow with only small differences on whether the power deposition is located on the low field side or on the high field side. With LH current drive the magnetic shear was varied from slightly positive to negative. The improved coupling (through the use of plasma shaping and CD4) allowed up to 3.4 MW of PLH in internal transport barrier (ITB) plasmas with more than 15 MW of combined NBI and ICRF heating. The q-profile with negative magnetic shear and the ITB could be maintained for the duration of the high heating pulse (8 s). Fast ions have been produced in JET with ICRF to simulate alpha particles: by using third harmonic 4He heating, beam injected 4He at 120 kV were accelerated to energies above 2 MeV, taking advantage of the unique capability of JET to use NBI with 4He and to confine MeV class ions. ICRF heating was used to replicate the dynamics of alpha heating and the control of an equivalent Q = 10 `burn' was simulated
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