SRF2011 - List of Authors (Ge, G.M.)

Paper	Title	Page
THPO015	Repair SRFCavity by Re-Melting Surface Defects via High Power Laser Technique	740
	G.M. Ge CLASSE, Ithaca, New York, USA E. Borissov, L.D. Cooley, D.T. Hicks, T.H. Nicol, J.P. Ozelis, J. Ruan, D.A. Sergatskov Fermilab, Batavia, USA G. Wu ANL, Argonne, USA
	As the field emission is gradually under control in recent SRF activities, cavity performance is limited by hard quench in the most case. Surface defect has been identified as one of main reasons caused cavity quench scattering cavity accelerating gradient from 12 MV/m to 40 MV/m. Laser processing is able to re-shape the steep flaws to be flat and smooth surface. In Fermilab, a sophisticated laser repair system has been built for 1.3GHz low performance SRF cavity which is limited by surface defect. The pit in a 1.3GHz single-cell cavity was re-melted by high power laser pulse, cavity took 30 μm light Electropolishing after that. The gradient achieved 39MV/m in initial run; after another 30 μm Electropolishing, it achieved 40 MV/m. The improved laser repair system is able to re-melt the surface defect in one meter long 9-cell SRF cavity. It successfully re-melted a pit in 9-cell SRF cavity TB9ACC017.

THPO051	Laser Re-Melting Influence on Nb Properties: Geometrical and Chemical Aspects	846
	A.V. Dzyuba, L.D. Cooley, E. Toropov Fermilab, Batavia, USA A.V. Dzyuba NSU, Novosibirsk, Russia G.M. Ge CLASSE, Ithaca, New York, USA G. Wu ANL, Argonne, USA
	We present recent results on Laser re-melting system used to smoothen niobium surfaces of superconducting RF cavities in order to overcome quench. In the work we studied both chemical and geometrical aspects of the melting by means of electron backscattered diffraction microscopy and laser confocal microscopy. BCP, EP and HF impacts have been investigated on both single and large grain niobium samples. Appropriate post processing has been suggested.

Paper

Title

Page

Repair SRFCavity by Re-Melting Surface Defects via High Power Laser Technique

740

G.M. Ge
CLASSE, Ithaca, New York, USA
E. Borissov, L.D. Cooley, D.T. Hicks, T.H. Nicol, J.P. Ozelis, J. Ruan, D.A. Sergatskov
Fermilab, Batavia, USA
G. Wu
ANL, Argonne, USA

As the field emission is gradually under control in recent SRF activities, cavity performance is limited by hard quench in the most case. Surface defect has been identified as one of main reasons caused cavity quench scattering cavity accelerating gradient from 12 MV/m to 40 MV/m. Laser processing is able to re-shape the steep flaws to be flat and smooth surface. In Fermilab, a sophisticated laser repair system has been built for 1.3GHz low performance SRF cavity which is limited by surface defect. The pit in a 1.3GHz single-cell cavity was re-melted by high power laser pulse, cavity took 30 μm light Electropolishing after that. The gradient achieved 39MV/m in initial run; after another 30 μm Electropolishing, it achieved 40 MV/m. The improved laser repair system is able to re-melt the surface defect in one meter long 9-cell SRF cavity. It successfully re-melted a pit in 9-cell SRF cavity TB9ACC017.

THPO051

Laser Re-Melting Influence on Nb Properties: Geometrical and Chemical Aspects

846

A.V. Dzyuba, L.D. Cooley, E. Toropov
Fermilab, Batavia, USA
A.V. Dzyuba
NSU, Novosibirsk, Russia
G.M. Ge
CLASSE, Ithaca, New York, USA
G. Wu
ANL, Argonne, USA

We present recent results on Laser re-melting system used to smoothen niobium surfaces of superconducting RF cavities in order to overcome quench. In the work we studied both chemical and geometrical aspects of the melting by means of electron backscattered diffraction microscopy and laser confocal microscopy. BCP, EP and HF impacts have been investigated on both single and large grain niobium samples. Appropriate post processing has been suggested.