7th SRF Materials Workshop
July 16-17, 2012
Thomas Jefferson National Accelerator Facility
Newport News, VA
Abstract Submissions
Please refer to the Call for Presentations below . All presentations must identify which of the topics they will address. Ten minutes will be allotted for each presentation and should conform to the following guidelines:
- Keep it short -- 5 slides excluding title and acknowledgment
- Get to the point-- propose or reiterate workshop questions -- supply information that furthers discussion, and propose new lines of work
- Speak! Do not write text and read it. Use the space on your slides for plots and illustrations. Tell us the story instead -- it's a workshop after all and the format will be very informal
- Do NOT simply recycle conference and previous workshop information. Follow the guidelines!
- Have back-up slides handy if the discussion seeks further information on what you presented.
E-mail proposed title and abstract to Lance Cooley (ldcooley@fnal.gov) or Charlie Reece (reece@jlab.org) by Monday, 25 June.
Call for Presentations
| End uses require economical MVs, this implies high Q (e.g. surface resistance below a few nΩ if at 2 K) and high EAcc (e.g. surface magnetic field exceeding 150 mT and surface electric field above 100 MV/m). Materials discussions should be relevant to the improvement of Q, EAcc, and the cost drivers associated with these parameters. |
All proposed contributions must identify which of the following topics are to be addressed. For example, ("I.B.2 and II.A.2").
Topics for Contributions
I: Drivers of materials R&D--The basic motivation - Functional needs and vexing questions:
- Theoretical understanding
- Understanding RF and SRF behavior
- Heat transfer and thermal behavior
- What is an ideal material or ideal surface?
- How can we best model practical surfaces based on the present characterization techniques?
- Bridging to performance of real materials
- What material features produce
- quenches below 150 mT surface field?
- non-linear rf losses below 150 mT surface field?
- increase in the RF surface resistance below 100 mT surface field?
- How do we prevent the material features above from occurring? What material forming and/or processing methods can minimize the occurrence of the above, for the minimum cost?
- How are surface resistance (Rs) and Q(E) affected by
- impurities?
- grain boundaries?
- surface layers?
- topography and length scale?
- secondary or combined effects (e.g. diffusion of impurities down grain boundaries)?
- How can we make various characterizations relevant, given that
- Q(E) and Rs can be measured for cavities but physical properties, structure, chemical properties, and topography of the actual RF surface cannot be probed easily without destroying the cavity or causing it to be re-processed?
- materials properties, structure, topography, and other important information can be extracted from small samples over arbitrary length scales, but Q(E), Rs, and RF behavior cannot be probed easily?
Discussion: What ideas or models are most useful and immediately applicable?
In other words, how do we describe the target surface and how can it be obtained reliably?
Summary discussion question: What aspects of R&D are most applicable to improving performance and yield? These aspects should drive materials R&D.
II: Current materials and processing R&D in Universities, Labs, and Industry
A -- Raw material, forming, and welding
- How should we improve material information and specifications?
- Do aspects of forming and welding instigate problems in later processing?
Discussion: Are there opportunities to integrate material processing with downstream chemistry? Will this solve problems?
B -- Surface preparation
- How confidently and reproducibly is a given surface created?
- What surfaces are being produced? How—what physical and chemical mechanisms lead to the surface features seen?
- How do different preparation techniques change surfaces?
- What aspects are contributed by tooling, process, or set-up?
Discussion: What is optimum and what needs improvement? What alternates are viable and why should they be exploited? What drawbacks should we be attacking while advancing alternate ideas?
C -- "Final" processing
- How does hydrogen de-gas baking affect the final surface?
- What happens upon re-formation of surface oxides?
- What changes occur during low-temperature baking?
- What happens when the clean surface is exposed?
- What happens with the final surface is re-processed?
Discussion: What are the important differences in the final surface structures and properties left by final processing steps? What changes need to be made, or what new aspects should be tried?
D -- Surface science techniques to address the above questions
- How do we bridge between inspections and characterizations on cavities and surface science conducted on small samples?
- Physical probes, structure
- Chemical probes, spectroscopy
- Surface states and surface properties
Discussion: What techniques are most useful and immediately applicable?
E -- Property measurements to address the above questions
- How do we compare properties measured for small samples with Q vs E Acc and other metrics of cavities?
- Normal-state and superconductivity property measurements
Discussion: What techniques are most useful and immediately applicable?
F -- Materials forming and surface treatments to address the above questions
Discussion: What techniques are most useful and immediately applicable?