IPAC2012 - List of Authors (You, Y.)

Paper	Title	Page
TUPPD069	Schottky-Enabled Photoemission and Dark Current Measurements - Toward an Alternate Approach to Fowler-Nordheim Plot Analysis	1563
	E.E. Wisniewski, W. Gai, J.G. Power ANL, Argonne, USA H. Chen, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You TUB, Beijing, People's Republic of China A. Grudiev, W. Wuensch CERN, Geneva, Switzerland E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Field-emitted dark current, a major gradient-limiting factor in RF cavities, is usually analyzed via Fowler-Nordheim (FN) plots. Traditionally, field emission is attributed to geometrical perturbations on the bulk surface whose field enhancement factor (beta) and the emitting area (A) can be extracted from the FN plot. Field enhancement factors extracted in this way are typically much too high (1 to 2 orders of magnitude) to be explainable by either the geometric projection model applied to the measured surface roughness or by field enhancement factors extracted from Schottky-enabled photoemission measurements. We compare traditional analysis of FN plots to an alternate approach employing local work function variation. This is illustrated by comparative analysis of recent dark current and Schottky-enabled photoemission data taken at Tsinghua S-band RF gun. We conclude by describing a possible experimental plan for discrimination of variation of local work function vs. local field enhancement.

Paper

Title

Page

Schottky-Enabled Photoemission and Dark Current Measurements - Toward an Alternate Approach to Fowler-Nordheim Plot Analysis

1563

E.E. Wisniewski, W. Gai, J.G. Power
ANL, Argonne, USA
H. Chen, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You
TUB, Beijing, People's Republic of China
A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Field-emitted dark current, a major gradient-limiting factor in RF cavities, is usually analyzed via Fowler-Nordheim (FN) plots. Traditionally, field emission is attributed to geometrical perturbations on the bulk surface whose field enhancement factor (beta) and the emitting area (A) can be extracted from the FN plot. Field enhancement factors extracted in this way are typically much too high (1 to 2 orders of magnitude) to be explainable by either the geometric projection model applied to the measured surface roughness or by field enhancement factors extracted from Schottky-enabled photoemission measurements. We compare traditional analysis of FN plots to an alternate approach employing local work function variation. This is illustrated by comparative analysis of recent dark current and Schottky-enabled photoemission data taken at Tsinghua S-band RF gun. We conclude by describing a possible experimental plan for discrimination of variation of local work function vs. local field enhancement.