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Cavity development

Cavity development . Rebecca Seviour. Operating Cavities in an Magnetic field. Where do the electrons go. 6 μ. 7 μ. Initial Particle Data Input (X,Y,Z) (Vx,Vy,Vz). Compute New Particle Data by Integration . Use Comsol to Extract (E, B) Field Parameters. Secondary Electron Emission.

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Cavity development

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  1. Cavity development Rebecca Seviour

  2. Operating Cavities in an Magnetic field

  3. Where do the electrons go...... 6 μ 7 μ Initial Particle Data Input (X,Y,Z) (Vx,Vy,Vz) Compute New Particle Data by Integration Use Comsol to Extract (E, B) Field Parameters Secondary Electron Emission FEA Analyses at the Point of Impact Extraction of Particle Data at Point of Impact

  4. As received Electropolished Ra(nm) 101 Rq(nm) 136 Ra(nm) 89 Rq(nm) 118

  5. As received Electropolished Before

  6. Need to do the experiment to prove .......

  7. Generic Problem Q R.L.Geng, PAC 2003 E Field (Mv/m)

  8. FP7 – EuCard Thin Films Examining phenomena limit current performance and investigating alternative coating techniques Several mechanisms for the thin film Q-drop[i]ii],[iii]; 200 MHz ,  ~ 40 nm Layer thickness ~ 10 m High Rinterface Nb Low

  9. High Rinterface Nb CERN, Nb on Cu

  10. Renormalisation of N by induced condensate (Proximity Effect) Quasiparticle current Contribution from conversion of low energy quasiparticle current into condensate current (Andreev Reflection) Superconductor Normal Conductor High Rinterface Nb

  11. Tip piezo Microfabricated cantilever AFM tip AFM photodetector laser Sample Sample piezotransducer Ultrasonic Force Microscope: Measuring Strain and Elasticity • Such elasticity variations are linked with • Local surface and subsurface material composition • Subsurface strain variations (they affect local elastic moduli via third order elastic constants) • UFM allows surface topography to be mapped simultaneously with the material composition and strain Nb (850 nm) on Si

  12. Towards a High Temperature SC RF Cavity ? Conventional SCRF (Nb) – Require He Cryosats (< 4 K) HTc SC - Operate >30 K HTc SC RF - Minehara (1990) considered HTc RF Cavity resonator made from isostaticaly pressed YBCO & BSCCO. Achieving Q > 10^6 at 30K. - Others considering the use of HTC Thin Film

  13. Bulk HTS Cavity limited by several factors, HTS have high residual resistance ratios,  f Transport properties very sensitive to imperfections. This gives rise to low current in the superconductor. HTS are extremely sensitive to the right stoichiometry and oxygen content.

  14. Some experimental RF work has been done on Proximity effect - Sputtered Cu on Nb - Rs of Cu reduced > 50% - SC is shielded from magnetic field

  15. Experiment Hybrid wall Coaxial coupler Detachable wall Normal Metal Detachable wall HTS 2 Hybrid walls • Working at 10 GHz (small sizes for ALD), create a number of hybrid proximity effect walls for evaluation ( Q, Rs, λ, ξ, , surface properties: stress, strain, elasticity) • repeat Cu /Nb experiments • asses various HTC (MagnisiumDiboride, BaKBiO) • asses various N metals (silver, lead, Cu) • Try various coating techniques

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