Nb₃Sn at Fermilab: Exploring Performance

Posen, Sam; Lee, Jaeyel; Melnychuk, Oleksandr; Pischalnikov, Yuriy; Seidman, David N.; Sergatskov, Dmitri; Tennis, B.

doi:10.18429/jacow-srf2019-thfub1

Cited by 3 publications

(5 citation statements)

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“…Progress has continued. The best case of a flat Q vs E curve out to 23 MV/m has been achieved at Fermilab [152,153,154] The performance at 4.2 K is also very attractive showing Q 0 > 10 10 at gradient of 18 MV/m. Latest films have smaller surface roughness (by a factor of 2), smaller thickness (1 µm vs 2-3 µm) and smaller grain size (0.7 µm vs 1.2 µm).…”

Section: Nb 3 Snmentioning

confidence: 99%

“…A15 compounds (a series of inter metallic compounds with the chemical formula A 3 B, where A is a transition metal and B can be any element) are intermetallic and brittle in the bulk form, so SRF structures are produced as a thin layer on the inner surface of an already formed structure. Nb 3 Sn is the most explored compound with the best results [152,153,154], but does not as yet give as good performance as with Nb cavities. The A15 phase is in the composition range of 18-25% Sn.…”

Section: Nb 3 Snmentioning

confidence: 99%

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The International Linear Collider (Report to Snowmass 2021)

Aryshev¹,

Behnke²,

Berggren³

et al. 2022

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The International Linear Collider (ILC) is on the table now as a new global energyfrontier accelerator laboratory taking data in the 2030's. The ILC addresses key questions for our current understanding of particle physics. It is based on a proven accelerator technology. Its experiments will challenge the Standard Model of particle physics and will provide a new window to look beyond it. This document brings the story of the ILC up to date, emphasizing its strong physics motivation, its readiness for construction, and the opportunity it presents to the US and the global particle physics community.

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Section: Nb 3 Snmentioning

confidence: 99%

Section: Nb 3 Snmentioning

confidence: 99%

The International Linear Collider (Report to Snowmass 2021)

Aryshev¹,

Behnke²,

Berggren³

et al. 2022

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“…The use of Nb3Sn thin films inside of niobium or copper cavities are considered. Currently, Nb3Sn films are fabricated inside single cell and multicell cavities by Sn vapor diffusion [1,[4][5][6]. Magnetron sputtering is considered as a potential alternative to fabricate Nb3Sn SRF cavities [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Microstructural and Superconducting Radiofrequency Properties of Multilayer Sequentially Sputtered Nb₃Sn films

Sayeed

Eremeev

Owen

et al. 2021

IEEE Trans. Appl. Supercond.

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Nb3Sn is considered as a potential candidate for superconducting radiofrequency cavities for particle acceleration due to its higher transition temperature of 18.3 K and higher superheating field of 400 mT. Nb3Sn films can be grown inside the surface of a Nb cavity by sequentially sputtering multiple layers of Nb and Sn thin films followed by annealing at 950 °C for 3 h. We report on the properties of Nb3Sn films grown on Nb substrates by magnetron sputtering. The films' crystal structure, surface morphology, and composition were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The films had a polycrystalline Nb3Sn structure with a fine-grain surface and an atomic Sn composition of ~23%. The RF surface resistance of the films was measured for different temperatures at 7.4 GHz to understand the feasibility of this method for the SRF application. The RF surface resistance of the films was 5 mΩ at 12 K, which is about 2 orders of magnitude higher than 60 µΩ previously measured in Nb3Sn films grown by Sn vapor diffusion. The sputtered film had a superconducting transition at 17.2 K, which is also lower than 17.9 K observed in Nb3Sn film prepared by vapor diffusion.

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“…A Q 0 of ∼3x10 10 at 4.4 K is needed to achieve 10 MV/m with conduction cooling. An improved Nb 3 Sn coating has already attained this Q 0 in a recent test 19 in the Fermilab VTS. For comparison, we show representative gradients measured in the VTS on the cavity before Nb 3 Sn coating.…”

mentioning

confidence: 95%

“…The attainable E acc with one cryocooler can be pushed up by improving the Q 0 of our cavity. The ongoing efforts for Nb 3 Sn coating optimization have already produced a Q 0 of ∼3x10 10 at 10 MV/m cw on a similar 650 MHz single-cell cavity 19 in the Fermilab VTS. The corresponding dissipation of ∼1.1 W at 4.4 K is now in the regime of cryocooler conduction cooling as marked in Fig.…”

mentioning

confidence: 99%

First demonstration of a cryocooler conduction cooled superconducting radiofrequency cavity operating at practical cw accelerating gradients

Dhuley

Posen

Geelhoed

et al. 2020

Supercond. Sci. Technol.

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We demonstrate practical accelerating gradients on a superconducting radiofrequency (SRF) accelerator cavity with cryocooler conduction cooling, a cooling technique that does not involve the complexities of the conventional liquid helium bath. A single cell 650 MHz Nb 3 Sn cavity coupled using high purity aluminum thermal links to a 4 K pulse tube cryocooler, generated accelerating gradients up to 6.6 MV/m at 100% duty cycle. The operation was carried out with the cavity-cryocooler assembly in a simple vacuum vessel, completely free of circulating liquid cryogens. We anticipate that this simple cryocooling technique will make the SRF technology accessible to accelerator researchers with no access to full-stack helium cryogenic systems. Furthermore, the technique can lead to SRF based compact sources of high average power electron beams for environmental and industrial applications.Electron irradiation is a proven technique for environmental protection applications such as the treatment of industrial/municipal wastewater, flue gases, sewage sludge, etc. and has been demonstrated on several pilot scale projects 1 . For electron irradiation to be competitive on the large scale with existing treatment methods, electron beam (e-beam) sources capable of providing beam energy of 1−10 MeV, megawattclass average beam power, and high wall-plug efficiency (>50%) are needed 2 . The sources must also be robust, reliable, and have turn-key operation to be viable in the harsh environment expected around these applications 2 . Compact sources with smaller footprints and lower infrastructure cost are also preferred.E-beam sources using superconducting radiofrequency (SRF) cavities as the beam accelerator can meet several of the above requirements. A meter-long or even a shorter structure of standard niobium cavities 3 or of low-dissipation Nb 3 Sn cavities 4 , both of which easily generate accelerating gradients >10 MV/m, can be an electron source with the desired beam energy. The low surface resistance of SRF cavities reduces their surface losses and provides high efficiency transfer of the input RF power to the beam, which can help to achieve the wall-plug efficiency target. The low surface resistance also facilitates constructing cavities with a larger aperture and allows RF operation with 100% duty cycle (continuous wave or cw mode), both of which are favorable for generating and efficiently transporting beams of very high average power. SRF cavities, however, need operation at cryogenic temperatures and are conventionally cooled by immersion in baths of liquid helium held near 2−4.5 K. The cryogenic infrastructure 5 needed for compressing, liquefying, distributing, recovering, and storing helium as well as expert cryogenic operators 6 needed for oversight run counter to the robustness, high reliability, compactness, and turn-key operation desired in industrial settings.An approach to simplify the helium cryogenic infrastructure and reduce its footprint is to integrate a closed-cycle 4 K cryocooler into an SRF cryomodule and ...

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Nb₃Sn at Fermilab: Exploring Performance

Cited by 3 publications

References 0 publications

The International Linear Collider (Report to Snowmass 2021)

The International Linear Collider (Report to Snowmass 2021)

Microstructural and Superconducting Radiofrequency Properties of Multilayer Sequentially Sputtered Nb₃Sn films

First demonstration of a cryocooler conduction cooled superconducting radiofrequency cavity operating at practical cw accelerating gradients

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Nb₃Sn at Fermilab: Exploring Performance

Cited by 3 publications

References 0 publications

The International Linear Collider (Report to Snowmass 2021)

The International Linear Collider (Report to Snowmass 2021)

Microstructural and Superconducting Radiofrequency Properties of Multilayer Sequentially Sputtered Nb3Sn films

First demonstration of a cryocooler conduction cooled superconducting radiofrequency cavity operating at practical cw accelerating gradients

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Product

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Microstructural and Superconducting Radiofrequency Properties of Multilayer Sequentially Sputtered Nb₃Sn films