On fully superconducting rectifiers and fluxpumps. A review. Part 2: Commutation modes, characteristics and switches

Klundert, L.J.M. van de; Kate, H. Ten

doi:10.1016/0011-2275(81)90002-3

Cited by 59 publications

(24 citation statements)

References 6 publications

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“…During time t=t 1 and t=t 2 the total flux in the loop increases, and the left branch experiences a fast change in field, which generates a loss (which can be considered as a dynamic resistance since the field in left branch changes much faster than the current in the loop, otherwise it can be considered as an AC loss resistance). During time t=t 3…”

Section: Fig 2 Schematic Drawing Of a Superconducting Loop Experienmentioning

confidence: 99%

“…The key point of these flux pumps is how a DC voltage is induced by external fields, which has also been confusing for years. The DC transformer which predates the Flux Pumps described by Van Klundert [2,3] et al appears in Gieaver [1] who pointed out that flux motion can be used to induce a DC voltage in a superconductor and described a rectifier based on a superconducting switch. Following their work, we will reveal that varying resistivity of type II superconductors due to flux flow is the origin of the DC voltage and therefore flux pumping.…”

Section: Introductionmentioning

confidence: 99%

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Origin of dc voltage in type II superconducting flux pumps: field, field rate of change, and current density dependence of resistivity

Geng¹,

Matsuda²,

Fu³

et al. 2016

J. Phys. D: Appl. Phys.

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Superconducting flux pumps are the kind of devices which can generate direct current into superconducting circuit using external magnetic field. The key point is how to induce a DC voltage across the superconducting load by AC fields. Giaever [1] pointed out flux motion in superconductors will induce a DC voltage, and demonstrated a rectifier model which depended on breaking superconductivity. Klundert et al. [2, 3] in their review(s) described various configurations for flux pumps all of which relied on inducing the normal state in at least part of the superconductor. In this letter, following their work, we reveal that a variation in the resistivity of type II superconductors is sufficient to induce a DC voltage in flux pumps and it is not necessary to break superconductivity. This variation in resistivity is due to the fact that flux flow is influenced by current density, field intensity, and field rate of change. We propose a general circuit analogy for travelling wave flux pumps, and provide a mathematical analysis to explain the DC voltage. Several existing superconducting flux pumps which rely on the use of a travelling magnetic wave can be explained using the analysis enclosed. This work can also throw light on the design and optimization of flux pumps.

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Section: Fig 2 Schematic Drawing Of a Superconducting Loop Experienmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Origin of dc voltage in type II superconducting flux pumps: field, field rate of change, and current density dependence of resistivity

Geng¹,

Matsuda²,

Fu³

et al. 2016

J. Phys. D: Appl. Phys.

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“…(1) = ∇ × H J (2) =ρ E J (3) 0 r =µ µ B H (4) 0 r To solve Eq. 5, the relative permeability and resistivity are needed for each material.…”

Section: D H-formulationmentioning

confidence: 99%

“…It is also tantalizing to understand the physics behind these devices where the concept of flux motion, resistance, and electric field in the diamagnetic material is in line with Faraday's Law. [1] Low-T c Superconducting (LTS) flux pumps [2] [3] have been developed for decades. In these devices the superconductor is at least partially driven normal to allow flux motion.…”

Section: Introductionmentioning

confidence: 99%

Modeling methodology for a HTS flux pump using a 2D H-formulation

Geng

Coombs

2018

Supercond. Sci. Technol.

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Flux pumps are the kind of devices that can magnetize closed superconducting magnets in a gradual manner. High-T c Superconducting (HTS) flux pumps are particularly promising for high field applications, due to the fact that lossless HTS coils are unavailable. The physics of these devices is also attractive. In this paper, we propose a modeling methodology for a transformer-rectifier HTS flux pump switched by dynamic resistance. A finite element model is built in Comsol and solved by 2D H-formulation. The simulation result is verified by experimental data. The simulation will give a clear picture of how flux pumping occurs in the superconductor. It will show flux motion across a superconductor by shifting the electric central line, which is a unique nature of type-II superconductors. This work may be interesting in the understanding of magnetization of High-T c Superconductors. Recently, Campbell [22] proposed a finite element model to calculate flux pumping using 2D A-formulation. His result showed that flux pumping occurs under CSM, and field dependence of J c facilitates flux pumping. His result, however, did not show that flux pumping is associated with the dynamic resistance effect. In Ref. [23] and Ref. [24], modeling technique for dynamic resistance was proposed using T-formulation and H-formulation respectively. In this paper, we further these studies to show how dynamic resistance incurred flux pumping can be simulated using H-Formulation with finite element software. We will present a clear picture of how flux travel across a superconductor transporting no direct current.

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“…The process is repeated and the coil will be charged to a high current. A full rectifier can also be found in [30] [31]. Depending on how the switches are operated, the flux pump can be classified into the following categories.…”

Section: Mechanismmentioning

confidence: 99%