اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدHysteretic ac losses in a superconductor strip between flat magnetic shields
143
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Hysteretic ac losses in a thin, current-carrying superconductor strip located between two flat magnetic shields of infinite permeability are calculated using Beans model of the critical state. For the shields oriented parallel to the plane of the strip, penetration of the self-induced magnetic field is enhanced, and the current dependence of the ac loss resembles that in an isolated superconductor slab, whereas for the shields oriented perpendicular to the plane of the strip, penetration of the self-induced magnetic field is impaired, and the current dependence of the ac loss is similar to that in a superconductor strip flanked by two parallel superconducting shields. Thus, hysteretic ac losses can strongly augment or, respectively, wane when the shields approach the strip.
قيم البحث
اقرأ أيضاً
The problem of calculating the ac losses in a superconductor strip with a transport current placed inside superconducting environments is studied analytically in the frame of the critical state model. Exact results obtained by the method of images fo
r the commonly employed flat ground plates are used to derive power losses and, consequently, the nonlinear resistance depending on the ac frequency, current amplitude and the distance to the ground plates. The resistance is strongly reduced when the distance between the strip and the shields becomes small.
Numerical simulations of hysteretic ac losses in a tubular superconductor/paramagnet heterostructure subject to an oscillating transverse magnetic field are performed within the quasistatic approach, calling upon the COMSOL finite-element software pa
ckage and exploiting magnetostatic-electrostatic analogues. It is shown that one-sided magnetic shielding of a thin, type-II superconducting tube by a coaxial paramagnetic support results in a slight increase of hysteretic ac losses as compared to those for a vacuum environment, when the support is placed inside; a spectacular shielding effect with a possible reduction of hysteretic ac losses by orders of magnitude, however, ensues, depending on the magnetic permeability and the amplitude of the applied magnetic field, when the support is placed outside.
A current-carrying superconducting strip partly penetrated by magnetic flux and surrounded by a bulk magnet of high permeability is considered. Two types of samples are studied: those with critical current controlled by an edge barrier dominating ove
r the pinning, and those with high pinning-mediated critical current masking the edge barrier.It is shown for both cases that the current distribution in a central flux-free part of the strip is strongly affected by the actual shape of the magnetic surroundings. Explicit analytical solutions for the sheet current and self-field distributions are obtained which show that, depending on the geometry, the effect may suppress the total loss-free transport current of the strip or enhance it by orders of magnitude. The effect depends strongly on the shape of the magnet and its distance to the superconductor but only weakly on the magnetic permeability.
A simple analytical expression is presented for hysteretic ac loss $Q$ of a superconducting strip simultaneously exposed to an ac transport current $I_0cosomega t$ and a phase-different ac magnetic field $H_0cos(omega t+theta_0)$. On the basis of Bea
ns critical state model, we calculate $Q$ for small current amplitude $I_0ll I_c$, for small magnetic field amplitude $H_0ll I_c/2pi a$, and for arbitrary phase difference $theta_0$, where $I_c$ is the critical current and $2a$ is the width of the strip. The resulting expression for $Q=Q(I_0,H_0,theta_0)$ is a simple biquadratic function of both $I_0$ and $H_0$, and $Q$ becomes maximum (minimum) when $theta_0=0$ or $pi$ ($theta_0=pi/2$).
This paper presents the analytical and numerical analysis of fluctuational dynamics of ac hysteretic SQUID. It has been demonstrated, that the most important parameter for the improvement of the hysteretic SQUID sensitivity is the ratio between the p
ump and the characteristic frequencies but not their absolute values. The resonant behavior of signal-to-noise ratio as function of the pump frequency has been observed and the narrow area for the optimal pump frequency range is indicated.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
