Flux Pump Research Articles

Jc(B) transformer rectifier flux pump optimisation via simulation

Abstract Superconducting power supplies commonly known as flux pumps are becoming viable products in various industries. In this work we investigate magnetically switched ( J c ( B ) ) half-wave transformer rectifier flux pumps (TRFPs) via a simulation previously validated against an experimental system. Upgrades to the model are introduced, namely the transition to a fully hysteretic transformer reluctance model and the introduction of a conduction cooling thermal model. The conduction cooling model allows direct comparison between liquid cryogen and conduction cooled systems, highlighting the distinct variations in response. This study focuses on parameter sweeps over some of the most important aspects of a TRFP such as; input power, cooling paths and switch length. The findings from these variable sweeps shed light on how to best design the different aspects of a TRFP for most applications and the conclusions drawn throughout this work can be applied to most TRFP types. Some of the major findings from this work are; i. the need for dedicated cooling busses in TRFP switches, ii. that increased switch lengths increase voltage generation but negatively impact cooling effectiveness iii. that the reduction of the metallic coatings surrounding commercial coated conductors results in larger switch voltages.

Design and initial test results of a space-bound flux pump to energize the Hēki mission’s superconducting magnet

Despite repeated proposals to utilize superconducting magnets in space since at least the 1970s, examples of their use remain scant. One of the technical challenges is to maintain suitable cryogenic temperatures on a spacecraft. This challenge can be alleviated by the use of flux pumps to reduce the required cryogenic cooling power needed to energize the superconducting magnet. This paper describes the design and initial test results of the flux pump to fulfill the requirements of the Hēki mission that will operate a high-temperature superconducting magnet on an external platform of the International Space Station. A transformer-based, self-rectifier architecture was chosen for the flux pump. An effective circuit model used to design its electromagnetic properties and finite-element modelling used in its mechanical and thermal design. Liquid nitrogen tests were used to demonstrate that the electrical performance of the flux pump meets requirements. Higher-fidelity tests using flight-like copies of the hardware and software were undertaken and validated the thermal modelling. These tests also featured the continuous operation of the flux pump in a conduction-cooled setting for over 100 hours, reflecting an inherent reliability of this technology. Whilst further testing and flight qualification remains to be completed, we anticipate an on-orbit demonstration of this flux pump technology in February 2025. Such a demonstration will signal a maturing of this emerging superconducting technology for both in-space and terrestrial applications.

Excitation Test of YBCO Tape at 45 K With Through-Wall Linear-Motor Type Flux Pump

Excitation Test of YBCO Tape at 45 K With Through-Wall Linear-Motor Type Flux Pump

A full-bridge flux pump using two switches: numerical model and experimental prototype

Abstract High-temperature superconducting (HTS) magnets are promising in high field applications. However, due to inevitable joint resistance and flux creep, HTS magnets still face challenges in maintaining field stability in their closed-loop operation. HTS flux pumps can charge closed HTS magnets wirelessly, thus allowing lower cryogenic loading and more flexible arrangements in HTS magnet systems. In this work, a full-bridge flux pump using two AC field-controlled switches is proposed, which can charge HTS magnets during whole cycles. Therefore, the charging speed of the proposed full-bridge flux pump is at least one time larger than half-bridge flux pumps. A numerical model and an experimental prototype are developed to verify the working principle of the proposed full-bridge flux pump. Simulation and experimental tests are carried out to investigate the working characteristics of the proposed flux pump. The proposed flux pump has huge potential in the application scenarios where high charging speed is required.

Design of Superconducting Motor Based on Through-Wall Excitation of Linear-Motor Type Flux Pump

Design of Superconducting Motor Based on Through-Wall Excitation of Linear-Motor Type Flux Pump

Feedback Control of Superconducting Current Based on Linear-Motor Type Magnetic Flux Pump

Feedback Control of Superconducting Current Based on Linear-Motor Type Magnetic Flux Pump

Research Progress of Conduction-Cooled HTS Magnets Wireless Charging Technology-HTS Flux Pumps

Research Progress of Conduction-Cooled HTS Magnets Wireless Charging Technology-HTS Flux Pumps

Limitations of the DC Output Voltage From HTS Flux Pumps

Limitations of the DC Output Voltage From HTS Flux Pumps

The Flux Pumping Behavior of High Temperature Superconducting Tapes With a Linearly Moving Electromagnet

The Flux Pumping Behavior of High Temperature Superconducting Tapes With a Linearly Moving Electromagnet

Test of Two Kilo-Amp Linear-Motor Type Flux Pumps With Converged Output Current Over 3.1 kA

Test of Two Kilo-Amp Linear-Motor Type Flux Pumps With Converged Output Current Over 3.1 kA

Circuit Model for HTS Flux Pump With Flux Conservation, Dynamic Resistance, and Flux Flow

Circuit Model for HTS Flux Pump With Flux Conservation, Dynamic Resistance, and Flux Flow

Design and Performance of a Linear Flux Pump for the Frascati Coil Cold Test Facility

Design and Performance of a Linear Flux Pump for the Frascati Coil Cold Test Facility

Airplane motors employing superconducting DC field windings and conventional conductor AC windings

Many organizations are developing compact lightweight highly efficient rotating machines for airplane applications. These machines include permanent magnets for excitation and an iron-core with and without superconducting windings. Air-core (no magnetic iron) machines have the potential to be the most lightweight and efficient. Such machines can use superconductors for both DC excitation field coils and AC armature coils, which need conductors under development, like MgB2 and Bi2212. If liquid-hydrogen (LH2) is available on a plane and can be used as a coolant, it becomes feasible to develop machines with AC armature coils made from conventional conductors like copper, aluminium, and high-conductivity aluminium.This paper describes conceptual designs for a 3 MW, 4,500 RPM motor employing REBCO CORC conductor for the DC field coils and conventional conductor Litz cable for the AC armature coils cooled by LH2 available on the plane. Both rotor and stator coils are contained in separate cryostats. The DC excitation coils on the rotor are operated at 40 K to work successfully with a brushless flux pump exciter. Likewise, stator AC coils are cooled with available LH2 to take advantage of the lower resistivity of conventional conductors at cryogenic temperatures. Motor size, mass and losses are compared for stator windings employing copper, aluminium, and high-conductivity aluminium (Hyper-Al). Compared with copper and aluminium machines, the machine employing Hyper-Al has smaller size, mass and total losses.

Fast Current Regulation and Persistent Current Maintenance of High-Temperature Superconducting Magnets With Contact Power Supply and Flux Pump

Fast Current Regulation and Persistent Current Maintenance of High-Temperature Superconducting Magnets With Contact Power Supply and Flux Pump

Influence of Flux Pinning on the Open-Circuit Voltage of a Dynamo-Type High-Tc Superconducting Flux Pump

Influence of Flux Pinning on the Open-Circuit Voltage of a Dynamo-Type High-Tc Superconducting Flux Pump

Sawtooth suppression by flux pumping on HBT-EP

This study examines the mechanisms underlying sawtooth suppression in the High Beta Tokamak-Extended Pulse (HBT-EP) device. It is observed that strong-intensity sawtooth activities correlate with reduced-amplitude magnetohydrodynamics (MHD) edge modes which are identified as m/n=3/1 external kink modes, while sawtooth suppression correlates with larger and saturated edge mode amplitudes. To further investigate these correlations, the plasma–wall coupling was manipulated by adjusting the positions of the conducting walls in HBT-EP. It was found that strong sawtooth events occur when the normalized wall radius b/a is within a critical value. This implies that the plasma–wall distance must be sufficiently small to ensure effective stabilization of the edge mode. Even slight differences in major radius result in significantly different discharge styles, categorized as ‘sawtoothing discharges’ and ‘sawtooth-suppressed discharges’ respectively. Through a series of mode structure analyses, we confirm the coexistence and coupling of the m/n=1/1 helical core, m/n=2/1 tearing mode, and m/n=3/1 external kink mode during sawtooth-suppression, and that this coupling induces anomalous current broadening. Based on these findings, we conclude that sawtooth suppression in the HBT-EP tokamak is consistent with the process of magnetic flux pumping.

3D electromagnetic modelling for high‐temperature superconducting dynamo flux pumps using T‐A formulation

AbstractA high‐temperature superconducting (HTS) dynamo flux pump can inject DC currents into closed‐loop HTS magnets without contact. It enables the realisation of current‐lead‐free or even through‐wall charging systems for high‐field applications such as nuclear magnetic resonance/magnetic resonance imaging (MRI) magnets, fusion reactors and accelerators. Researchers have proposed many simulation models to understand the working principle of HTS dynamos, few of which are in 3D because of converging problems. Therefore, the influences of many key 3D parameters in the HTS dynamo are scarcely reported. The authors propose an efficient 3D modelling method of the HTS dynamo based on the T‐A formulation. The rotating magnets are modelled by a ring‐shaped permanent magnet with space‐time‐variant remanent flux density to avoid moving meshes. This, together with the T‐A formulation, makes the 3D model efficient and universal. The accuracy of the model is verified by the experimental instantaneous and time‐integrated dynamic voltages. Using this model, the authors present systematic case studies to thoroughly explore the influences of the key parameters of a dynamo flux pump on the dynamic voltage and losses. The proposed modelling method and results could significantly benefit the design and optimisation of HTS dynamos for high‐field magnets.

Characterization of linear motor flux pump using H-formulation

H-formulation is an effective method for electromagnetic simulation analysis of superconductors. This paper innovatively uses H-formulation to simulate and analyze the operation characteristics of magnetic flux pump operating in linear-motor pattern. Via COMSOL Multiphysics, this paper establishes a two-dimensional electrical equipment simulation model that comprehensively compares excitation conditions of triangular and trapezoidal current waves to investigate the effects of the working excitation waveforms’ frequency and amplitude on the operating features of the equipment. The following operation control laws are revealed: the current amplitude has a linear control effect on the mean value of superconductor surface electric field and the average amount of air-slot density of magnetic flux, the current frequency has no effect on the air-gap magnetic field waveform, and the regulation effect of the excitation frequency on the average value of superconductor surface strength of electric field is related to the waveforms. Finally, the equivalent circuit of the pumping model is established, and two interrelated L-R equivalent circuits are designed by quadratic substitution, and the final pumping current reaches 43A.

Flux pumping studies and Ti peaking by q-profile shaping using ECCD in ASDEX Upgrade

On ASDEX Upgrade a prioritized ‘advanced Tokamak’ program has been run during the last two experimental campaigns, focusing on the effect of non-standard current profiles on the behavior of high beta plasmas. Two lines of non-standard (i.e. non-sawtoothing) q-profiles are followed: (1) plasma self-organization of centrally flat q-profiles (qmin ≈ 1) via ‘flux pumping’, here based on a naturally occurring continuous (1,1) mode and (2) externally shaped q-profiles with qmin > 1, allowing for more experimental freedom of the q-profile to be established. The advantages and requirements of both concepts are discussed. The invited presentation at the workshop focuses on specific effects of Electron Cyclotron Current Drive (ECCD). With respect to flux pumping it could be shown that increasing the plasma beta raises the flux pumping capability. More central coECCD can be redistributed if beta is increased. This is in line with qualitative theory. For the case with qmin > 1, it is shown that small variations of the ECCD profile can modify the peaking of the central ion temperature. For larger radii no significant changes of the kinetic profiles have been observed as the q-profile is changed. Hfactors have not exceeded 1.2, well below the assumptions of several models for steady state tokamak operation. To achieve these changes of q at larger radii we have used ctr-ECCD in the plasma center, increasing the ohmic current globally. The net effect of central ctr-ECCD and increased ohmic current is a strong off-axis current drive, allowing H-modes with Te ≈ Ti ≈ 8 keV and n¯e ≈ 6 · 1019m−3 ≈ 0.5 nGW at q95 = 4 to be run stationary with qmin ≈ 1.4. The design of these discharges was strongly supported by inter-shot model based optimization.

Antibacterial Effects of Nanocomposites on Efflux Pump Expression and Biofilm Production in Pseudomonas aeruginosa: A Systematic Review.

Pseudomonas aeruginosa is an opportunistic gram-negative pathogen with multiple mechanisms of resistance to antibiotics. This systematic review aimed to study the antibacterial effects of nanocomposites on efflux pump expression and biofilm production in P. aeruginosa. The search was conducted from January 1, 2000, to May 30, 2022, using terms such as (P. aeruginosa) AND (biofilm) AND (antibiofilm activity) AND (anti-Efflux Pump Expression activity) AND (nanoparticles) AND (Efflux Pump Expression) AND (Solid Lipid NPS) AND (Nano Lipid Carriers). Many databases are included in the collection, including ScienceDirect, PubMed, Scopus, Ovid, and Cochrane. A list of selected articles was retrieved by using the relevant keywords. A total of 323 published papers were selected and imported into the Endnote library (version X9). Following the removal of duplicates, 240 were selected for further processing. Based on the titles and abstracts of the articles, 54 irrelevant studies were excluded. Among the remaining 186 articles, 54 were included in the analysis because their full texts were accessible. Ultimately, 74 studies were selected based on inclusion/exclusion criteria. Recent studies regarding the impact of NPs on drug resistance in P. aeruginosa found that various nanostructures were developed with different antimicrobial properties. The results of our study suggest that NPs may be a feasible alternative for combating microbial resistance in P. aeruginosa by blocking flux pumps and inhibiting biofilm formation.