Physics and Accelerator Applications of RF Superconductivity

Shepard, K.W.; Sundelin, Ron

doi:10.1146/annurev.ns.43.120193.003223

Cited by 32 publications

(18 citation statements)

References 27 publications

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“…In superconducting cavities in the presence of rf fields various mechanisms for the breakdown of superconductivity are associated with characteristics of the surface, e.g., the presence of surface impurities or steps caused by grain boundaries. 12 Moreover surface properties, namely specular vs. diffuse reflection, are known to affect the electromagnetic response of impure superconductors. 34 Therefore, it would be important to explore theoretically the impact of surface imperfections on the superheating field.…”

Section: Summary and Open Problemsmentioning

confidence: 99%

Temperature dependence of the superheating field for superconductors in the high-κLondon limit

Catelani

Sethna

2008

Phys. Rev. B

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We study the metastability of the superheated Meissner state in type II superconductors with κ ≫ 1 beyond Ginzburg-Landau theory, which is applicable only in the vicinity of the critical temperature. Within Eilenberger's semiclassical approximation, we use the local electrodynamic response of the superconductor to derive a generalized thermodynamic potential valid at any temperature. The stability analysis of this functional yields the temperature dependence of the superheating field. Finally, we comment on the implications of our results for superconducting cavities in particle accelerators.

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Section: Summary and Open Problemsmentioning

confidence: 99%

Temperature dependence of the superheating field for superconductors in the high-κLondon limit

Catelani

Sethna

2008

Phys. Rev. B

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“…The metastability of the Meissner state is of interest in the design of resonance RF cavities in particle accelerators, where H sh places a fundamental limit on the maximum accelerating field [2]. As type II superconducting materials are being considered in cavity designs, a precise calculation of H sh in this regime is of value.…”

Section: Introductionmentioning

confidence: 99%

Superheating field of superconductors within Ginzburg-Landau theory

2011

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We study the superheating field of a bulk superconductor within Ginzburg-Landau theory, which is valid near the critical temperature. We calculate, as functions of the Ginzburg-Landau parameter κ, the superheating field H sh and the critical momentum kc characterizing the wavelength of the instability of the Meissner state to flux penetration. By mapping the two-dimensional linear stability theory into a one-dimensional eigenfunction problem for an ordinary differential equation, we solve the problem numerically. We demonstrate agreement between the numerics and analytics, and show convergence to the known results at both small and large κ. We discuss the implications of the results for superconducting RF cavities used in particle accelerators.

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“…It has been calculated in the framework of the BCS theory [1] by Mattis and Bardeen [2] and independently by Abrikosov, Gor'kov and Khalatnikov [3] as early as 1958. Much of the experimental work has been driven by applications to the fields of fast electronics and particle accelerators [4]. In the latter case, most of the attention has been given to the development of superconducting RF cavities, operated in the 0.1 to 5 GHz range, and producing as large as possible an electric field along their axis, typically in the 10 MV/m range.…”

Section: Introductionmentioning

confidence: 99%

Study of the surface resistance of superconducting niobium films at 1.5 GHz

Benvenuti

Calatroni

Campisi

et al. 1999

Physica C: Superconductivity

129

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A systematic study of superconducting properties of niobium films sputtered on the inner wall of radiofrequency cavities is presented. The measured quantities include in particular the response to 1.5 GHz microwaves, the critical temperature, the penetration depth and the magnetic penetration field. In addition to films grown in different gas discharges (Xe, Kr, Ar and Ar/Ne mixtures) and to films grown on substrates prepared under different conditions, the study includes also bulk niobium cavities. The surface resistance is analysed in terms of its dependence on temperature, on RF field and, when relevant, on the density of trapped fluxons. A simple parameterisation is found to give a good fit to the data. Once allowance for the presence of impurities and defects is made by means of a single parameter, the electron mean free path, good agreement with BCS theory is observed. The fluxon-induced losses are studied in detail and their dependence on RF field, on temperature and on the density of trapped fluxons is analysed. The residual resistance is observed to be essentially uncorrelated with the other variables, suggesting that it is dominantly extragranular. In occasions very low residual resistances, in the nΩ range, have been maintained over a broad range of RF field, indicating the absence of significant fundamental limitations specific to the film technology in practical applications such as the production of accelerating cavities for particle accelerators.

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Physics and Accelerator Applications of RF Superconductivity

Cited by 32 publications

References 27 publications

Temperature dependence of the superheating field for superconductors in the high-κLondon limit

Temperature dependence of the superheating field for superconductors in the high-κLondon limit

Superheating field of superconductors within Ginzburg-Landau theory

Study of the surface resistance of superconducting niobium films at 1.5 GHz

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