Residual Resistance Data From Cavity Production Projects at Jefferson Lab

Ciovati, Gianluigi; Geng, Rongli; Mammosser, J.; Saunders, Jeffrey

doi:10.1109/tasc.2010.2087305

Cited by 8 publications

(6 citation statements)

References 8 publications

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“…A positive result from the multi-cell cavities was the confirmation of maintaining high Q 0 -values (greater than 1×10 10 ) up to B p > 100 mT, as it was measured on singlecell cavities. The values of the residual resistance were deduced from the Q 0 -values at low field, as described in [19], for the test results shown in Figs. 3 and 4 and are lower than those obtained on fine-grain cavities at the same frequency, as shown in Fig.…”

Section: Multi-cell Cavitiesmentioning

confidence: 99%

“…5. The values for the fine-grain cavities are the average of several tens of cavities built, processed and tested at JLab: 805 MHz SNS cavities (treated by BCP), 1497 MHz CEBAF refurbishment cavities (treated by BCP) and 1300 MHz ILC cavities (treated by EP) [19].…”

Section: Multi-cell Cavitiesmentioning

confidence: 99%

“…Residual resistance values obtained from the low-field Q 0 (2.0 K) for fine-grain (FG) [19] and large-grain (LG) cavities at different frequencies.…”

Section: Figurementioning

confidence: 99%

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America’s Overview of Superconducting Science and Technology of Ingot Niobium

Kneisel¹,

Myneni²,

Ciovati³

et al. 2011

AIP Conference Proceedings

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This contribution will present an overview of the results from R&D programs in the USA over the past four years towards the development of ingot Niobium as a viable alternative material to fabricate SRF cavities for particle accelerators. Activities at several laboratories and universities include fabrication, surface treatment and RF testing of single-and multi-cell cavities and studies of the thermal, mechanical and superconducting properties of samples from ingots of different purity. Possible advantages of ingot niobium over standard fine-grain (ASTM 6) are discussed and a streamlined treatment procedure to fully exploit those advantages is proposed.

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Section: Multi-cell Cavitiesmentioning

confidence: 99%

Section: Multi-cell Cavitiesmentioning

confidence: 99%

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America’s Overview of Superconducting Science and Technology of Ingot Niobium

Kneisel¹,

Myneni²,

Ciovati³

et al. 2011

AIP Conference Proceedings

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“…To further understand the effect of the thermal resistance on the performance of SRF cavity, the large grain cavity TD5 was measured with a temperature mapping system built at Jefferson lab [14], based on the system developed at Cornell University [15]. The temperature mapping system consists of the custom-made sensors from 100  Allen-Bradley carbon resistors (5%, 1/8 W) calibrated against a calibrated Cernox temperature sensor immersed in the helium bath.…”

Section: B Rf Test and Temperature Mappingmentioning

confidence: 99%

Role of thermal resistance on the performance of superconducting radio frequency cavities

Dhakal

Ciovati

Myneni

2017

Phys. Rev. Accel. Beams

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Thermal stability is an important parameter for the operation of the superconducting radio frequency (SRF) cavities used in particle accelerators. The rf power dissipated on the inner surface of the cavities is conducted to the helium bath cooling the outer cavity surface and the equilibrium temperature of the inner surface depends on the thermal resistance. In this manuscript, we present the results of direct measurements of thermal resistance on 1.3 GHz single cell SRF cavities made from high purity large grain and fine grain niobium as well as their rf performance for different treatments applied to outer cavity surface in order to investigate the role of the Kapitza resistance to the overall thermal resistance and to the SRF cavity performance. The results show no significant impact of the thermal resistance to the SRF cavity performance after chemical polishing, mechanical polishing or anodization of the outer cavity surface. Temperature maps taken during the rf test show non-uniform heating of the surface at medium rf fields. Calculations of Q 0 (B p ) curves using the thermal feedback model show good agreement with experimental data at 2 K and 1.8 K when a pair-braking term is included in the calculation of the BCS surface resistance. These results indicate local intrinsic non-linearities of the surface resistance, rather than purely thermal effects, to be the main cause for the observed field dependence of Q 0 (B p ).

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“…The residual resistance for bulk niobium is calculated by (2.27) in [22] showing a quadratic dependency on the frequency. From the measurements presented in [24], R res can be estimated to a few nanoohms, hence, is a minor contribution to the total surface resistance that we will consider later. The calculations are limited by our incomplete knowledge of the material properties represented by the residual resistance ratio RRR [7].…”

Section: Rf Simulationmentioning

confidence: 99%

Comparison of coaxial higher order mode couplers for the CERN Superconducting Proton Linac study

Papke

Gerigk

Rienen

2017

Phys. Rev. Accel. Beams

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Higher order modes (HOMs) may affect beam stability and refrigeration requirements of superconducting proton linacs such as the Superconducting Proton Linac, which is studied at CERN. Under certain conditions beam-induced HOMs can accumulate sufficient energy to destabilize the beam or quench the superconducting cavities. In order to limit these effects, CERN considers the use of coaxial HOM couplers on the cutoff tubes of the 5-cell superconducting cavities. These couplers consist of resonant antennas shaped as loops or probes, which are designed to couple to potentially dangerous modes while sufficiently rejecting the fundamental mode. In this paper, the design process is presented and a comparison is made between various designs for the high-beta SPL cavities, which operate at 704.4 MHz. The rf and thermal behavior as well as mechanical aspects are discussed. In order to verify the designs, a rapid prototype for the favored coupler was fabricated and characterized on a low-power test-stand.

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Residual Resistance Data From Cavity Production Projects at Jefferson Lab

Cited by 8 publications

References 8 publications

America’s Overview of Superconducting Science and Technology of Ingot Niobium

America’s Overview of Superconducting Science and Technology of Ingot Niobium

Role of thermal resistance on the performance of superconducting radio frequency cavities

Comparison of coaxial higher order mode couplers for the CERN Superconducting Proton Linac study

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