Plasma Treatment Of Bulk Niobium Surfaces For Srf Cavities

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Plasma Treatment of Bulk Niobium Surfaces for SRF Cavities

Author : L. Phillips
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis Plasma Treatment of Bulk Niobium Surfaces for SRF Cavities by : L. Phillips

Download or read book Plasma Treatment of Bulk Niobium Surfaces for SRF Cavities written by L. Phillips and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two types of electric discharges were used to demonstrate the validity of plasma surface treatment for superconducting radio-frequency (SRF) cavities. The experiments were performed on disc-shaped Nb samples and compared with identical samples treated with buffer chemical polishing (BCP) techniques. Surface analysis indicates comparable or superior properties of plasma-treated samples. These promising results are still preliminary and additional work is in progress.

Plasma Treatment of Bulk Niobium Surface for SRF Cavities

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis Plasma Treatment of Bulk Niobium Surface for SRF Cavities by :

Download or read book Plasma Treatment of Bulk Niobium Surface for SRF Cavities written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulsed electric discharges were used to demonstrate the validity of plasma surface treatment of superconducting radio-frequency cavities. The experiments were performed on disc-shaped Nb samples and compared with identical samples treated with buffer chemical polishing techniques. The results of several standard surface analytical techniques indicate that plasma-treated samples have comparable or superior properties regarding the surface roughness and composition.

Plasma Treatment of Niobium SRF Cavity Surfaces

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (873 download)

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Book Synopsis Plasma Treatment of Niobium SRF Cavity Surfaces by :

Download or read book Plasma Treatment of Niobium SRF Cavity Surfaces written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma based surface modification provides an excellent opportunity to eliminate non- superconductive pollutants in the penetration depth region of the SRF cavity surface and to remove mechanically damaged surface layer improving surface roughness. We have demonstrated on flat samples that plasma etching in Ar / Cl2 of bulk Nb is a viable alternative surface preparation technique to BCP and EP methods, with comparable etching rates. The geometry of SRF cavities made of bulk Nb defines the use of asymmetric RF discharge configuration for plasma etching. In a specially designed single cell cavity with sample holders, discharge parameters are combined with etched surface diagnostics to obtain optimum combination of etching rates, roughness and homogeneity in a variety of discharge types, conditions, and sequences. The optimized experimental conditions will ultimately be applied to single cell SRF cavities.

Plasma Treatment of Single-Cell Niobium SRF Cavities

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (873 download)

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Book Synopsis Plasma Treatment of Single-Cell Niobium SRF Cavities by :

Download or read book Plasma Treatment of Single-Cell Niobium SRF Cavities written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Superconducting radio frequency cavities of bulk Niobium are integral components of particle accelerators based on superconducting technology. Wet chemical processing is the commonly used procedure for impurities and surface defects removal and surface roughness improvement, both required to improve the RF performance of the cavity. We are studying plasma etching as an alternate technique to process these cavities. The uniformity of the plasma sheath at the inner wall of the cavity is one prerequisite for its uniform etching. We are developing electro-optic diagnostic techniques to assess the plasma uniformity. Multiple electro-optical probes are placed at different locations of the single cell cavity to diagnose the electrical and optical properties of the plasma. The electrical parameters are required to understand the kinetic nature of the plasma and the optical emission spectroscopy provides the spatial distribution of radicals in the plasma. The spatial variation of the plasma parameters inside the cavity and their effect on the etching of niobium samples placed at different locations in the cavity will be presented.

PLASMA ETCHING RATES AND SURFACE COMPOSITION OF BULK NIOBIUM TREATED IN Ar

Author :
Publisher :
ISBN 13 :
Total Pages : 55203 pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis PLASMA ETCHING RATES AND SURFACE COMPOSITION OF BULK NIOBIUM TREATED IN Ar by :

Download or read book PLASMA ETCHING RATES AND SURFACE COMPOSITION OF BULK NIOBIUM TREATED IN Ar written by and published by . This book was released on 2008 with total page 55203 pages. Available in PDF, EPUB and Kindle. Book excerpt: To achieve theoretically predicted values of the accelerating fields in superconducting radiofrequency (SRF) cavities, their inside surface should be fairly smooth and free of impurities. Thus, surface preparation is the critical step in production of SRF cavities. Plasma etching process is a dry chemistry technique that can be used to achieve these requirements. It is based on interaction between reactive halogen species produced in the glow discharge and the surface. During this process, volatile Nb halides are evaporated from the surface of Nb, removing the mechanically damaged and contaminated layer. We present a treatment of bulk Nb samples in the Ar/Cl2 microwave discharge. We have shown that etching rates of bulk Nb as high as 1.5 mm/min can be achieved without introducing impurities in Nb. The rate dependence on various discharge parameters and reactive gas composition is presented. Surface composition and topology measurements were carried out before and after plasma treatment.

Plasma Processing of SRF Cavities for the Next Generation Of Particle Accelerators

Author :
Publisher :
ISBN 13 :
Total Pages : 14 pages
Book Rating : 4.:/5 (951 download)

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Book Synopsis Plasma Processing of SRF Cavities for the Next Generation Of Particle Accelerators by :

Download or read book Plasma Processing of SRF Cavities for the Next Generation Of Particle Accelerators written by and published by . This book was released on 2015 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cost-effective production of high frequency accelerating fields are the foundation for the next generation of particle accelerators. The Ar/Cl2 plasma etching technology holds the promise to yield a major reduction in cavity preparation costs. Plasma-based dry niobium surface treatment provides an excellent opportunity to remove bulk niobium, eliminate surface imperfections, increase cavity quality factor, and bring accelerating fields to higher levels. At the same time, the developed technology will be more environmentally friendly than the hydrogen fluoride-based wet etching technology. Plasma etching of inner surfaces of standard multi-cell SRF cavities is the main goal of this research in order to eliminate contaminants, including niobium oxides, in the penetration depth region. Successful plasma processing of multi-cell cavities will establish this method as a viable technique in the quest for more efficient components of next generation particle accelerators. In this project the single-cell pill box cavity plasma etching system is developed and etching conditions are determined. An actual single cell SRF cavity (1497 MHz) is plasma etched based on the pill box cavity results. The first RF test of this plasma etched cavity at cryogenic temperature is obtained. The system can also be used for other surface modifications, including tailoring niobium surface properties, surface passivation or nitriding for better performance of SRF cavities. The results of this plasma processing technology may be applied to most of the current SRF cavity fabrication projects. In the course of this project it has been demonstrated that a capacitively coupled radio-frequency discharge can be successfully used for etching curved niobium surfaces, in particular the inner walls of SRF cavities. The results could also be applicable to the inner or concave surfaces of any 3D structure other than an SRF cavity.

Improving the Work Function of the Niobium Surface of SRF Cavities by Plasma Processing

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (967 download)

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Book Synopsis Improving the Work Function of the Niobium Surface of SRF Cavities by Plasma Processing by :

Download or read book Improving the Work Function of the Niobium Surface of SRF Cavities by Plasma Processing written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An in situ plasma processing technique using chemically reactive oxygen plasma to remove hydrocarbons from superconducting radio frequency cavity surfaces at room temperature was developed at the spallation neutron source, at Oak Ridge National Laboratory. To understand better the interaction between the plasma and niobium surface, surface studies on small samples were performed. In this article, we report the results from those surface studies. The results show that plasma processing removes hydrocarbons from top surface and improves the surface work function by 0.51.0 eV. Improving the work function of RF surface of cavities can help to improve their operational performance.

Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2012 Edition

Author :
Publisher : ScholarlyEditions
ISBN 13 : 1481645854
Total Pages : 378 pages
Book Rating : 4.4/5 (816 download)

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Book Synopsis Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2012 Edition by :

Download or read book Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2012 Edition written by and published by ScholarlyEditions. This book was released on 2013-01-10 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Nuclear Physics. The editors have built Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Nuclear Physics in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Etching of Niobium Sample Placed on Superconducting Radio Frequency Cavity Surface in Ar/CL2 Plasma

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (873 download)

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Book Synopsis Etching of Niobium Sample Placed on Superconducting Radio Frequency Cavity Surface in Ar/CL2 Plasma by :

Download or read book Etching of Niobium Sample Placed on Superconducting Radio Frequency Cavity Surface in Ar/CL2 Plasma written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. It has been proven with flat samples that the bulk Niobium (Nb) removal rate and the surface roughness after the plasma etchings are equal to or better than wet etching processes. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders serve the purpose of diagnostic ports for the measurement of the plasma parameters and for the holding of the Nb sample to be etched. The plasma properties at RF (100 MHz) and MW (2.45 GHz) frequencies are being measured with the help of electrical and optical probes at different pressures and RF power levels inside of this cavity. The niobium coupons placed on several holders around the cell are being etched simultaneously. The etching results will be presented at this conference.

Passivated Niobium Cavities

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis Passivated Niobium Cavities by :

Download or read book Passivated Niobium Cavities written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A niobium cavity exhibiting high quality factors at high gradients is provided by treating a niobium cavity through a process comprising: 1) removing surface oxides by plasma etching or a similar process; 2) removing hydrogen or other gases absorbed in the bulk niobium by high temperature treatment of the cavity under ultra high vacuum to achieve hydrogen outgassing; and 3) assuring the long term chemical stability of the niobium cavity by applying a passivating layer of a superconducting material having a superconducting transition temperature higher than niobium thereby reducing losses from electron (cooper pair) scattering in the near surface region of the interior of the niobium cavity. According to a preferred embodiment, the passivating layer comprises niobium nitride (NbN) applied by reactive sputtering.

Niobium Thin Film Cavity Deposition by ECR Plasma

Author : H. L. Phillips
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis Niobium Thin Film Cavity Deposition by ECR Plasma by : H. L. Phillips

Download or read book Niobium Thin Film Cavity Deposition by ECR Plasma written by H. L. Phillips and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nb/Cu technology for superconducting cavities has proven to be over the years a viable alternative to bulk niobium. Energetic vacuum deposition is a very unique alternative method to grow niobium thin film on copper. Single crystal growth of niobium on sapphire substrate has been achieved as well as good surface morphology of niobium on small copper samples. The design of a cavity deposition system is in development. This paper presents the exploratory studies of the influence of the deposition energy on the Nb thin film properties. Several possible venues to achieve Nb/Cu cavity deposition with this technique are also discussed along with the design of the cavity deposition setup under development.

Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Application

Author : Liang Zhao (Ph. D.)
Publisher :
ISBN 13 :
Total Pages : 237 pages
Book Rating : 4.:/5 (971 download)

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Book Synopsis Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Application by : Liang Zhao (Ph. D.)

Download or read book Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Application written by Liang Zhao (Ph. D.) and published by . This book was released on 2015 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Applications

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (958 download)

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Book Synopsis Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Applications by :

Download or read book Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Applications written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Niobium cavities are important components in modern particle accelerators based on superconducting radio frequency (SRF) technology. The interior of SRF cavities are cleaned and polished in order to produce high accelerating field and low power dissipation on the cavity wall. Current polishing methods, buffered chemical polishing (BCP) and electro-polishing (EP), have their advantages and limitations. We seek to improve current methods and explore laser polishing (LP) as a greener alternative of chemical methods. The topography and removal rate of BCP at different conditions (duration, temperature, sample orientation, flow rate) was studied with optical microscopy, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). Differential etching on different crystal orientations is the main contributor to fine grain niobium BCP topography, with gas evolution playing a secondary role. The surface of single crystal and bi-crystal niobium is smooth even after heavy BCP. The topography of fine grain niobium depends on total removal. The removal rate increases with temperature and surface acid flow rate within the rage of 0~20 °C, with chemical reaction being the possible dominate rate control mechanism. Surface flow helps to regulate temperature and avoid gas accumulation on the surface. The effect of surface flow rate on niobium EP was studied with optical microscopy, atomic force microscopy (AFM), and power spectral density (PSD) analysis. Within the range of 0~3.7 cm/s, no significant difference was found on the removal rate and the macro roughness. Possible improvement on the micro roughness with increased surface flow rate was observed. The effect of fluence and pulse accumulation on niobium topography during LP was studied with optical microscopy, SEM, AFM, and PSD analysis. Polishing on micro scale was achieved within fluence range of 0.57~0.90 J/cm2, with pulse accumulation adjusted accordingly. Larger area treatment was proved possible by overlapping laser tracks at proper ratio. Comparison of topography and PSD indicates that LP smooths the surface in a way similar to EP. The optimized LP parameters were applied to different types of niobium surfaces representing different stages in cavity fabrication. LP reduces the sharpness on rough surfaces effectively, while doing no harm to smooth surfaces. Secondary ion mass spectrometer (SIMS) analysis showed that LP reduces the oxide layer slightly and no contamination occurred from LP. EBSD showed no significant change on crystal structure after LP.

Advance in Vertical Buffered Electropolishing on Niobium for Particle Accelerators*

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (873 download)

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Book Synopsis Advance in Vertical Buffered Electropolishing on Niobium for Particle Accelerators* by :

Download or read book Advance in Vertical Buffered Electropolishing on Niobium for Particle Accelerators* written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Niobium (Nb) is the most popular material that has been employed for making superconducting radio frequency (SRF) cavities to be used in various particle accelerators over the last couple of decades. One of the most important steps in fabricating Nb SRF cavities is the final chemical removal of 150 [mu]m of Nb from the inner surfaces of the SRF cavities. This is usually done by either buffered chemical polishing (BCP) or electropolishing (EP). Recently a new Nb surface treatment technique called buffered electropolishing (BEP) has been developed at Jefferson Lab. It has been demonstrated that BEP can produce the smoothest surface finish on Nb ever reported in the literature while realizing a Nb removal rate as high as 10 [mu]m/min that is more than 25 and 5 times quicker than those of EP and BCP(112) respectively. In this contribution, recent advance in optimizing and understanding BEP treatment technique is reviewed. Latest results from RF measurements on BEP treated Nb single cell cavities by our unique vertical polishing system will be reported.

Surface Studies of Acid-treated Niobium for Superconducting Radio Frequency Cavities

Author : David R. Smith
Publisher :
ISBN 13 :
Total Pages : 94 pages
Book Rating : 4.:/5 (572 download)

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Book Synopsis Surface Studies of Acid-treated Niobium for Superconducting Radio Frequency Cavities by : David R. Smith

Download or read book Surface Studies of Acid-treated Niobium for Superconducting Radio Frequency Cavities written by David R. Smith and published by . This book was released on 2004 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:

An Improved Surface Treatment for Superconducting Niobium Cavities

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Publisher :
ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (759 download)

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Book Synopsis An Improved Surface Treatment for Superconducting Niobium Cavities by :

Download or read book An Improved Surface Treatment for Superconducting Niobium Cavities written by and published by . This book was released on 1994 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Parameter Optimization for Laser Polishing of Niobium for SRF Applications

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Publisher :
ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (16 download)

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Book Synopsis Parameter Optimization for Laser Polishing of Niobium for SRF Applications by :

Download or read book Parameter Optimization for Laser Polishing of Niobium for SRF Applications written by and published by . This book was released on 2013 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface smoothness is critical to the performance of SRF cavities. As laser technology has been widely applied to metal machining and surface treatment, we are encouraged to use it on niobium as an alternative to the traditional wet polishing process where aggressive chemicals are involved. In this study, we describe progress toward smoothing by optimizing laser parameters on BCP treated niobium surfaces. Results shows that microsmoothing of the surface without ablation is achievable.