English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Plasma based surface modification of niobium is a promising alternative towet etching of superconducting radio frequency (SRF) cavities. The developmentof the technology based on Cl2/Ar plasma etching has to address several crucialparameters which influence the etching rate and surface roughness, andeventually, determine cavity performance. This includes dependence of theprocess on the frequency of the RF generator, gas pressure, power level, thedriven (inner) electrode configuration, and the chlorine concentration in thegas mixture during plasma processing. To demonstrate surface layer removal inthe asymmetric non-planar geometry, we are using a simple cylindrical cavitywith 8 ports symmetrically distributed over the cylinder. The ports are usedfor diagnosing the plasma parameters and as holders for the samples to beetched. The etching rate is highly correlated with the shape of the innerelectrode, radio-frequency (RF) circuit elements, chlorine concentration in theCl2/Ar gas mixtures, residence time of reactive species and temperature of thecavity. Using cylindrical electrodes with variable radius, large-surfacering-shaped samples and d.c. bias implementation in the external circuit wehave demonstrated substantial average etching rates and outlined thepossibility to optimize plasma properties with respect to maximum surfaceprocessing effect.

Plasma Processing of Large Curved Surfaces for SRF Cavity Modification