Observation of quenching-induced magnetic flux trapping using a magnetic field and temperature mapping system

Okada, Takafumi; Kako, E.; Masuzawa, M.; Sakai, Hiroshi; Ueki, Ryuichi; Umemori, Kensei; Tajima, T.

doi:10.1103/physrevaccelbeams.25.082002

Cited by 4 publications

(3 citation statements)

References 16 publications

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“…The rest of this review focuses on rf losses of Abrikosov vortices with normal cores [18]. Such vortices trapped by a random pinning potential of materials defects can bundle together, forming localized hotspots which have been revealed by temperature mapping of Nb cavities [30,79,80] and thin film structures [81,82], as well as by magnetic mapping [257][258][259]. Unlike hotspots caused by lossy materials defects, vortex hotspots can be moved or fragmented by temperature gradients produced by external heaters [119] or scanning laser [80,120,260,261] or electron [262,263] beams.…”

Section: Trapped Vorticesmentioning

confidence: 99%

Tuning microwave losses in superconducting resonators

Gurevich

2023

Supercond. Sci. Technol.

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Performance of superconducting resonators, particularly cavities for particle accelerators and micro cavities and thin film resonators for quantum computations and photon detectors has been improved substantially by recent materials treatments and technological advances. As a result, the niobium cavities have reached the quality factors $Q\sim 10^{11}$ at 1-2 GHz and 1.5 K and the breakdown radio-frequency (rf) fields $H$close to the dc superheating field of the Meissner state. These advances raise the question whether the state-of-the-art cavities are close to the fundamental limits, what these limits actually are, and to what extent the $Q$ and $H$ limits can be pushed by the materials nano structuring and impurity management. These issues are also relevant to many applications using high-Q thin film resonators, including single-photon detectors and quantum circuits. This topical review outlines basic physical mechanisms of the rf nonlinear surface impedance controlled by quasiparticles, dielectric losses and trapped vortices, as well as the dynamic field limit of the Meissner state. Sections cover ways of engineering an optimum quasiparticle density of states and superfluid density to reduce rf losses and kinetic inductance by pairbreaking mechanisms related to magnetic impurities, rf currents, and proximity-coupled metallic layers at the surface. A section focuses on mechanisms of residual surface resistance which dominates rf losses at ultra low temperatures. Microwave losses of trapped vortices and their reduction by optimizing the concentration of impurities and pinning potential are also discussed.

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Section: Trapped Vorticesmentioning

confidence: 99%

Tuning microwave losses in superconducting resonators

Gurevich

2023

Supercond. Sci. Technol.

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“…The Bardeen-Cooper-Schrieffer (BCS) resistance depends on temperature, and the residual resistance is the leftover resistance at zero temperature. Magnetic flux is quantized, and the magnetic flux in the superconductor is quantized with the magnetic flux quantum [39,40]. The trapped magnetic flux, which is the multiple of the magnetic flux quantum in Nb superconducting cavity, can be expressed as…”

Section: Magnetic Effect On Superconducting Cavitymentioning

confidence: 99%

Magnetic Heating Effect for Quarter-Wave Resonator (QWR) Superconducting Cavities

Kim¹,

Jeon²,

Jung³

et al. 2023

Preprint

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The magnetic heating effect for the superconducting quarter-wave resonator (QWR) cavities is investigated, and the Q slopes of the superconducting cavities are measured with an increasing accelerating field. Physical phenomena for zero-temperature limit are introduced. Bardeen–Cooper–Schrieffer (BCS) resistance and Casimir force are calculated for the zero-temperature limit. The vertical test is shown for the performance test of the quarter-wave resonator (QWR) cavities. The parameters for the quarter-wave resonator (QWR) cavity are presented. The Q slopes are measured as a function of an accelerating electric field at 4.2 K. The surface resistance of the superconducting cavity increases with an increasing peak magnetic field. The magnetic defects cause the degradation for the quality factor. From the magnetic degradation, we can find the magnetic moments of the superconducting cavities. All the quarter-wave resonator (QWR) cryomodules are installed in the tunnel, and beam commissioning is performed successfully.

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“…The BCS resistance depends on temperature, and the residual resistance is the leftover resistance at zero temperature. Magnetic flux is quantized, and the magnetic flux in the superconductor is quantized with the magnetic flux quantum [32,33]. The trapped magnetic flux, which is the multiple of the magnetic flux quantum in Nb superconducting cavity, can be expressed as [32]…”

Section: Magnetic Effect In a Superconducting Cavitymentioning

confidence: 99%

Magnetic Heating Effect for Quarter-Wave Resonator (QWR) Superconducting Cavities

Kim

Jeon

Jung

et al. 2023

QuBS

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In this paper, the magnetic heating effect of the superconducting quarter-wave resonator (QWR) cavities is investigated, and the Q slopes of the superconducting cavities are measured with an increasing accelerating field. Bardeen–Cooper–Schrieffer (BCS) resistance is calculated for the zero-temperature limit. The vertical test is shown for the performance test of the QWR cavities. The parameters for the QWR cavity are presented. The Q slopes are measured as a function of an accelerating electric field at 4.2 K. The surface resistance of the superconducting cavity increases with an increasing peak magnetic field. The magnetic defects degrade the quality factor. From the magnetic degradation, we determine the magnetic moments of the superconducting cavities. All quarter-wave resonator (QWR) cryomodules are installed in the tunnel, and beam commissioning is performed successfully.

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Observation of quenching-induced magnetic flux trapping using a magnetic field and temperature mapping system

Cited by 4 publications

References 16 publications

Tuning microwave losses in superconducting resonators

Tuning microwave losses in superconducting resonators

Magnetic Heating Effect for Quarter-Wave Resonator (QWR) Superconducting Cavities

Magnetic Heating Effect for Quarter-Wave Resonator (QWR) Superconducting Cavities

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