1 / 14

Recent DC spark results

Recent DC spark results. Antoine Descoeudres, Yngve Levinsen, Sergio Calatroni, Mauro Taborelli. Outline. Surface treatments of Cu samples Evolution of b during conditioning and BDR measurements. Outline. Surface treatments of Cu samples rolled sheet (reference) heat treatment milling

janine
Download Presentation

Recent DC spark results

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Recent DC spark results Antoine Descoeudres, Yngve Levinsen, Sergio Calatroni, Mauro Taborelli

  2. Outline • Surface treatments of Cu samples • Evolution of b during conditioning and BDR measurements

  3. Outline • Surface treatments of Cu samples • rolled sheet (reference) • heat treatment • milling • Subu • Electro-polishing

  4. ‘‘de-conditioning’’ due to spark damages (observed only with Cu) Cu standard sample (rolled sheet) • First 2 – 3 sparks : Eb = 350 – 400 MV/m, b = 15 – 20 • After a few sparks: ~ 170 MV/m, b ~ 50 • The delay before the first spark is usually very long (ms)

  5. Quantity of gas released during a spark : slightly less, but within error bars Cu + heat treatment at 875°C • Both electrodes treated in a brazing cycle (2h) • Same results as non-heated Cu (Eb, b, BDR…)

  6. good surface state at the start, like rolled sheet Cu + milling • Sample milled in the CERN workshop (no idea what the roughness may be…) • Standard behaviour :

  7. Eb = 200 MV/m, b = 20 – 35 Cu (milled) + Subu treatment • Subu : ~ 20 mm removed • The surface state at the start is not as good :

  8. Also a good surface state, comparable to standard Cu Cu (milled) + Electro-polishing • Electro-polishing: ~ 20 mm removed

  9. The first sparks destroy rapidly the benefit of a good surface preparation Surface treatments of Cu : summary • Surface treatments on Cu only affects the very first breakdowns • After a few sparks: ~ 170 MV/m, b ~ 50 for every samples And in RF ? Sparks are distributed over a much larger surface… Treatments are maybe still useful

  10. Outline • Surface treatments of Cu samples • Evolution of b during conditioning and BDR measurements

  11. Evolution of b during conditioning measurements • In the 2nd DC spark setup: automatization of b measurements  between each spark

  12. Evolution of b during conditioning measurements • Correlation between b and the next breakdown field • No correlation between b and the previous breakdown field b · Eb = cst

  13. Evolution of b during conditioning measurements • b · Eb is much less dispersed than Eb Local field : b · Eb = cst = 9.8 GV/m (± 0.2) for Cu

  14. Are small tips pulled by the field? (we need more data) Evolution of b during BDR measurements spark • ‘calm’ period  low b • b seems to increase (a few %) during a calm period if E is sufficiently high

More Related