Above v c the velocity amplitude grows approximately with the square root of the driving force because turbulent drag is proportional to the square of the velocity PRL1 . XIV, pp. In W. P. Halperin (Ed. The Landau critical velocity. Critical Velocity - Lancer la poursuite (Progress in Low Temperature Physics). The threshold velocity at which excitations of a given type acquire for the first time the negative energy is called the Landau critical velocity. McClintock PVE. Collective excitations determine a critical velocity below which the flow is dissipationless. It is easily understood that the critical velocity decreases with the decrease in the particle-particle interaction and disappears in the limit of an ideal gas because vc = minp "(p) jpj = 0 for "(p) = p2 2m. We also limit to such low fields that the deformation of the A phase order parameter ~1! 1 0. Landau critical velocity in weakly interacting Bose gases Gordon Baym, C. J. Pethick (Submitted on 29 Jun 2012) The flow of a uniform Bose gas at speeds greater than the Landau critical velocity, v_c, does not necessarily destroy superfluidity, but rather need only lead to a decrease of the superfluid mass density, {\rho}_s. ), Progress in Low Temperature Physics (Vol. Watch Landau critical velocity - kmhock on Dailymotion. the Landau criteria but in this case the critical velocity is smaller than the sound velocity due to the complicated excitation spectrum, as shown in Fig. Zeitschrift für Physik B Condensed Matter.

Investigations of the motion of conventional negative ions (electron bubbles) in He II under pressures above 11 bar have provided the only means of measuring the Landau critical velocity for roton creation, VL, and for studying supercritical dissipation at higher velocities. ONE-DIMENSIONAL CALCULATION We study flow in bulk 3He-A far from any walls. The flow of a uniform Bose gas at speeds greater than the Landau critical velocity v c does not necessarily destroy superfluidity, but rather needs only to lead to a decrease of the superfluid mass density ρ s . The main assumption in the present work is that the order param- eter ~1! c around Tc, where the Ginzburg-Landau critical velocity ;(\/2m)jGL21 is smaller than vd. 5.1(b). The flow of a uniform Bose gas at speeds greater than the Landau critical velocity, v_c, does not necessarily destroy superfluidity, but rather need only lead to a decrease of the superfluid mass density, {\rho}_s. III. Typically, these velocity amplitudes are in the range from mm/s up to almost m/s Vinen , and therefore much lower than the Landau critical velocity of about 50 m/s.

1995 Sep;98(3):429-434. https://doi.org/10.1007/BF01338419 towards the A1 phase can be neglected.

Main Question or Discussion Point .

wave function. In terms of the effective metric in superfluids, the region where the quasiparticle energy is negative represents the ergoregion, … Ions and the Landau critical velocity in He II. 1 The definition of Landau critical velocity is v L = min q { ω (q) q }, where ω (q) is the spectrum of excitations. Landau critical velocity in Helium-3 Thread starter andbe; Start date Feb 22, 2014; Feb 22, 2014 #1 andbe.