IPAC2014 - List of Authors (Wang, F.Y.)

Paper	Title	Page
THPRI076	Laser Triggered RF Breakdown Study Using an S-band Photocathode Gun	3943
	J.H. Shao, W. Gai ANL, Argonne, Illinois, USA H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, C.-X. Tang, L.X. Yan TUB, Beijing, People's Republic of China C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA F.Y. Wang SLAC, Menlo Park, California, USA
	A laser triggered RF breakdown experiment was carried out with an S-band photocathode gun at Tsinghua University for attempting understanding of the RF breakdown processes. By systematic measurement of the time dependence of the breakdown current at the gun exit and the stored RF energy in the cavity, one might gain insight into the time evolution of RF breakdown physics. A correlation of the stored energy and field emission current has been analysed with an equivalent circuit model. Experimental details and analysis methods are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI076
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THPRI077	Electric Field Enhancement Study using an L-band Photocathode Gun	3946
	J.H. Shao, W. Gai ANL, Argonne, Illinois, USA H.B. Chen, J. Shi TUB, Beijing, People's Republic of China C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA F.Y. Wang, L. Xiao SLAC, Menlo Park, California, USA
	RF breakdown in high gradient accelerating structures is a fundamental problem that is still needed better understanding. Past studies have indicated that field emission, which is usually represented by electric field enhancement (i.e. β) produced from the Fowler-Nordheim plot, is strongly coupled to the breakdown problem. A controlled surface study using a high gradient L-band RF gun is being carried out. With a flat cathode, the maximum electric field on the surface reached 10³ MV/m. And electric field as high as 565 MV/m on the surface was achieved by a pin-shaped cathode. The field enhancement factor was measured at different surface field during the conditioning process. Initial results of the study are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI077
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THPRI078	Experimental Study of Surface RF Magnetic Field Enhancement Caused by Closely Spaced Protrusions	3949
	F.Y. Wang, C. Adolphsen, J.P. Eichner, C.D. Nantista, L. Xiao SLAC, Menlo Park, California, USA
	The RF magnetic field enhancement between two closely spaced protrusions on a metallic surface has been studied theoretically. It is found that a large enhancement occurs when the field is perpendicular to the gap between the protrusions. This mechanism could help explain the melting that has been observed on cavity surfaces subjected to pulsed heating that would nominally be well below the melting temperature of the surface material. To test this possibility, an experiment was carried out in which a pair of copper “pins” was attached to the base plate of an X-band cavity normally used to study pulsed heating. Melting was observed between the pins when the predicted peak temperature was near or exceeded the copper melting temperature.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI078
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THPRI079	RF BREAKDOWN IN A GAS-FILLED TE01 CAVITY	3952
	F.Y. Wang, C. Adolphsen, C.D. Nantista SLAC, Menlo Park, California, USA
	An L-band (1.3 GHz) TE01 mode pillbox cavity has been designed to study rf breakdown in gas. Since there are no surface electric fields, effects from the electron interaction with the surface should not be present as in the DC breakdown case. A CCD camera was used to measure the integrated light pattern through holes in the cavity, and an ultrafast diode was used to observed the evolution of the plasma during breakdown. Some preliminary results of the tests are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI079
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Paper

Title

Page

Laser Triggered RF Breakdown Study Using an S-band Photocathode Gun

3943

J.H. Shao, W. Gai
ANL, Argonne, Illinois, USA
H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, C.-X. Tang, L.X. Yan
TUB, Beijing, People's Republic of China
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
F.Y. Wang
SLAC, Menlo Park, California, USA

A laser triggered RF breakdown experiment was carried out with an S-band photocathode gun at Tsinghua University for attempting understanding of the RF breakdown processes. By systematic measurement of the time dependence of the breakdown current at the gun exit and the stored RF energy in the cavity, one might gain insight into the time evolution of RF breakdown physics. A correlation of the stored energy and field emission current has been analysed with an equivalent circuit model. Experimental details and analysis methods are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI076

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRI077

Electric Field Enhancement Study using an L-band Photocathode Gun

3946

J.H. Shao, W. Gai
ANL, Argonne, Illinois, USA
H.B. Chen, J. Shi
TUB, Beijing, People's Republic of China
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
F.Y. Wang, L. Xiao
SLAC, Menlo Park, California, USA

RF breakdown in high gradient accelerating structures is a fundamental problem that is still needed better understanding. Past studies have indicated that field emission, which is usually represented by electric field enhancement (i.e. β) produced from the Fowler-Nordheim plot, is strongly coupled to the breakdown problem. A controlled surface study using a high gradient L-band RF gun is being carried out. With a flat cathode, the maximum electric field on the surface reached 10³ MV/m. And electric field as high as 565 MV/m on the surface was achieved by a pin-shaped cathode. The field enhancement factor was measured at different surface field during the conditioning process. Initial results of the study are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI077

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRI078

Experimental Study of Surface RF Magnetic Field Enhancement Caused by Closely Spaced Protrusions

3949

F.Y. Wang, C. Adolphsen, J.P. Eichner, C.D. Nantista, L. Xiao
SLAC, Menlo Park, California, USA

The RF magnetic field enhancement between two closely spaced protrusions on a metallic surface has been studied theoretically. It is found that a large enhancement occurs when the field is perpendicular to the gap between the protrusions. This mechanism could help explain the melting that has been observed on cavity surfaces subjected to pulsed heating that would nominally be well below the melting temperature of the surface material. To test this possibility, an experiment was carried out in which a pair of copper “pins” was attached to the base plate of an X-band cavity normally used to study pulsed heating. Melting was observed between the pins when the predicted peak temperature was near or exceeded the copper melting temperature.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI078

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRI079

RF BREAKDOWN IN A GAS-FILLED TE01 CAVITY

3952

F.Y. Wang, C. Adolphsen, C.D. Nantista
SLAC, Menlo Park, California, USA

An L-band (1.3 GHz) TE01 mode pillbox cavity has been designed to study rf breakdown in gas. Since there are no surface electric fields, effects from the electron interaction with the surface should not be present as in the DC breakdown case. A CCD camera was used to measure the integrated light pattern through holes in the cavity, and an ultrafast diode was used to observed the evolution of the plasma during breakdown. Some preliminary results of the tests are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI079

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)