| Paper | Title | Other Keywords | Page |
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| TUPMP040 | Impact of Flux Jumps on High-Precision Powering of Nb3Sn Superconducting Magnets | experiment, simulation, controls, superconducting-magnet | 1338 |
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| Nb3Sn superconducting magnets represent a technology enabler for future high-energy particle accelerators. A possible impediment, though, comes from flux jumps that, so far, could not be avoided by design unlike for NbTi technology. However, the impact of flux jumps on the powering has not been properly investigated to date. Flux jumps appear during current ramps at relatively low value of current and tend to disappear towards nominal current. They are usually detected as voltage jumps between different magnet coils but they might also produce overall voltage jumps across the magnet electrical terminals. Such jumps might perturb the power converter feedback control loop and therefore potentially jeopardize its precision performance during energy ramps. This work aims at : (i) presenting preliminary experimental test results on some HL-LHC Nb3Sn model and prototype magnets, and (ii) attempting to build a simplified electrical model of the flux jumps (with focus only at its interaction with the power converter feedback control loop). Such work is a starting point for outlining possible power converters control strategies able to minimize flux jumps impact on high-precision powering of Nb3Sn superconducting magnets. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP040 | ||
| About • | paper received ※ 23 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | ||
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| TUPTS118 | LASA Activities on Surface Treatment of Low-beta Elliptical Cavities | cavity, SRF, FEL, cathode | 2207 |
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| This paper describes the efforts made by LASA on the development of surface treatments for low-beta elliptical cavities, for the current series production of ESS and the foreseen series production of PIP-II. The traditional techniques of buffered chemical polishing and electropolishing are here discussed taking into account the industrial environment, the practical issues due to the size and geometry of such cavities and according to the required qualification values for quality factor and accelerating gradient. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS118 | ||
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | ||
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| WEPRB028 | Electromagnetic Design of the Low Beta Cavities for the JAEA ADS | cavity, SRF, linac, proton | 2870 |
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| The Japan Atomic Energy Agency (JAEA) is designing a superconducting CW proton linear accelerator for the ADS project. The superconducting region will use five types of radio frequency cavities. In the region from 2 to 180 MeV the acceleration will be done using Half Wave Resonator (HWR) and Single Spokes (SS) cavities. HWR cavities will accelerate the beam from 2 to 10 MeV with a geometrical beta of 0.08 and the SS ones will do from 10 to 180 MeV using two cavity families with geometrical betas of 0.16 and 0.43. The results of electromagnetic model design are presented and the comparison with similar cavities from other projects are included. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB028 | ||
| About • | paper received ※ 19 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | ||
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| WEPRB070 | Facile Deposition of Superconducting MgB2 Thin Films on Substrates: A Comparative Investigation of Electrochemical Deposition and Magnetron Sputtering Techniques | cavity, site, target, FEL | 2984 |
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Funding: Authors acknowledge the funding received under the Rutherford International Postdoctoral Fellowship Programme Coating of Copper cavities with a superconducting layer of MgB2 thin film is an attractive alternative to bulk Nb cavities. In this work, we investigate the application of two approaches-electrochemical deposition and magnetron sputtering of MgB2, to fabricate MgB2 films with potential accelerator applications. In the first approach, MgB2 powder dispersed in acetone was used as an electrolytic medium. Application of a DC voltage of 400 V between a graphite anode and a Copper film (serving as cathode), with the electrode distance maintained at ~2cm, resulted in the electrochemical deposition of MgB2 on the Cu surface. In an alternate approach, MgB2 in powder form was used directly for sputtering based deposition. The powder was initially compacted to form a thin layer that served as the magnetron target. Application of a pulsed DC power of 25W for 4 hours yielded MgB2 thin film on Si substrates. Samples were characterized by XPS analysis to ascertain their elemental composition, which confirmed the presence of Mg and B, in addition to traces of C and O as impurities. Surface morphology was determined using SEM characterization technique. Further work to determine the superconducting properties of the samples and fine tune the deposition processes for large scale MgB2 deposition inside actual RF cavities is in progress. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB070 | ||
| About • | paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | ||
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| WEPRB110 | Recent Results from Nb3Sn-Coated Single-cell Cavities Combined with Sample Studies at Jefferson Lab | cavity, experiment, SRF, niobium | 3066 |
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Funding: Partially authored by Jefferson Science Associates under contract no. DEAC0506OR23177. Supported by Office of High Energy Physics under grants DE-SC-0014475 and DE-SC-0018918. The critical temperature (~ 18 K) and superheating field (~ 425 mT) of Nb3Sn are almost twice that of niobium, thereby promising the higher quality factor and accelerating gradient at any given temperature compared to traditional SRF cavities made of niobium. It can enable higher temperature for cavity operation (4 K Vs. 2 K), resulting in significant reduction in both capital and operating cost for the cryoplant. Several single-cell cavities along with witness samples were coated with Nb3Sn to explore, understand and improve the coating process for betterment of cavity performance. RF measurements of coated cavities combined with material characterization of witness samples were employed to update the coating process. Following some modifications to the existing coating process, we were able to produce Nb3Sn cavity with quality factor ≥ 2.1010 for accelerating gradient up to 15 MV/m at 4 K, without any significant Q-slope. In this article, we will discuss recent results from several Nb3Sn coated single-cell cavities combined with material studies of witness samples. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB110 | ||
| About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | ||
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