34,275 research outputs found
Breakdown of adiabatic invariance in spherical tokamaks
Thermal ions in spherical tokamaks have two adiabatic invariants: the
magnetic moment and the longitudinal invariant. For hot ions, variations in
magnetic-field strength over a gyro period can become sufficiently large to
cause breakdown of the adiabatic invariance. The magnetic moment is more
sensitive to perturbations than the longitudinal invariant and there exists an
intermediate regime, super-adiabaticity, where the longitudinal invariant
remains adiabatic, but the magnetic moment does not. The motion of
super-adiabatic ions remains integrable and confinement is thus preserved.
However, above a threshold energy, the longitudinal invariant becomes
non-adiabatic too, and confinement is lost as the motion becomes chaotic. We
predict beam ions in present-day spherical tokamaks to be super-adiabatic but
fusion alphas in proposed burning-plasma spherical tokamaks to be
non-adiabatic.Comment: 6 pages, 8 figure
The spin alignment of galaxies with the large-scale tidal field in hydrodynamic simulations
The correlation between the spins of dark matter halos and the large-scale
structure (LSS) has been studied in great detail over a large redshift range,
while investigations of galaxies are still incomplete. Motivated by this point,
we use the state-of-the-art hydrodynamic simulation, Illustris-1, to
investigate mainly the spin--LSS correlation of galaxies at redshift of .
We mainly find that the spins of low-mass, blue, oblate galaxies are
preferentially aligned with the slowest collapsing direction () of the
large-scale tidal field, while massive, red, prolate galaxy spins tend to be
perpendicular to . The transition from a parallel to a perpendicular trend
occurs at in the stellar mass, in the g-r
color, and in triaxiality. The transition stellar mass decreases with
increasing redshifts. The alignment was found to be primarily correlated with
the galaxy stellar mass. Our results are consistent with previous studies both
in N-body simulations and observations. Our study also fills the vacancy in the
study of the galaxy spin--LSS correlation at using hydrodynamical
simulations and also provides important insight to understand the formation and
evolution of galaxy angular momentum.Comment: 9 pages, 6 figures, 1 table. Accepted for publication in ApJ, match
the proof versio
Strong laws of large numbers for sub-linear expectations
We investigate three kinds of strong laws of large numbers for capacities
with a new notion of independently and identically distributed (IID) random
variables for sub-linear expectations initiated by Peng. It turns out that
these theorems are natural and fairly neat extensions of the classical
Kolmogorov's strong law of large numbers to the case where probability measures
are no longer additive. An important feature of these strong laws of large
numbers is to provide a frequentist perspective on capacities.Comment: 10 page
P-wave pi pi amplitude from dispersion relations
We solve the dispersion relation for the P-wave pi pi amplitude.We discuss
the role of the left hand cut vs Castillejo-Dalitz-Dyson (CDD), pole
contribution and compare the solution with a generic quark model description.
We review the the generic properties of analytical partial wave scattering and
production amplitudes and discuses their applicability and fits of experimental
data.Comment: 10 pages, 7 figures, typos corrected, reference adde
The Tychonoff uniqueness theorem for the G-heat equation
In this paper, we obtain the Tychonoff uniqueness theorem for the G-heat
equation
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