2011 Particle Accelerator Conference - List of Authors (Cultrera, L.)

Paper

Title

Page

Cornell ERL Research and Development

729

C.E. Mayes, I.V. Bazarov, S.A. Belomestnykh, D.H. Bilderback, M.G. Billing, J.D. Brock, E.P. Chojnacki, J.A. Crittenden, L. Cultrera, J. Dobbins, B.M. Dunham, R.D. Ehrlich, M. P. Ehrlichman, E. Fontes, C.M. Gulliford, D.L. Hartill, G.H. Hoffstaetter, V.O. Kostroun, F.A. Laham, Y. Li, M. Liepe, X. Liu, F. Löhl, A. Meseck, A.A. Mikhailichenko, H. Padamsee, S. Posen, P. Quigley, P. Revesz, D.H. Rice, D. Sagan, V.D. Shemelin, E.N. Smith, K.W. Smolenski, A.B. Temnykh, M. Tigner, N.R.A. Valles, V. Veshcherevich, Y. Xie
CLASSE, Ithaca, New York, USA
S.S. Karkare, J.M. Maxson
Cornell University, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731.
Energy Recovery Linacs (ERLs) are proposed as drivers for hard X-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. The advantages of ERL lightsources will be explained, and the status of plans for such facilities will be described. In particular, Cornell University plans to build an ERL light source, and the preparatory research for its construction will be discussed. This will include the prototype injector for high current CW ultra-low emittance beams, superconducting CW technology, the transport of low emittance beams, halo formation from intrabeam scattering, the mitigation of ion effects, the suppression of instabilities, and front to end simulations. Several of these topics could become important for other modern light source projects, such as SASE FELs, HGHG FELs, and XFELOs.

Slides TUOBS2 [5.632 MB]

WEP244

Growth and Characterization of Bialkali Photocathodes for Cornell ERL Injector

1942

L. Cultrera, I.V. Bazarov, J.V. Conway, B.M. Dunham, Y. Li, X. Liu, K.W. Smolenski
CLASSE, Ithaca, New York, USA
S.S. Karkare, J.M. Maxson
Cornell University, Ithaca, New York, USA

The requirements of high quantum efficiency in the visible spectral range and that of an increased lifetime as compared to cesiated GaAs can be met by multi-alkali photocathodes, either CsKSb or NaKSb. In this paper we detail the procedures that allow the growth of thin films suitable for the ERL photoinjector operating at Cornell University. Quantum efficiency, spectral response, and surface characterization of deposited samples is presented. A load-locked multi-alkali cathode growth system is also described.

THOCN1

Cathodes for Photoemission Guns

2099

L. Cultrera
CLASSE, Ithaca, New York, USA

The last decade has seen a considerable interest in pursuit and realization of novel light sources such as Free Electron Lasers and Energy Recovery Linacs that promise to deliver unprecedented quality x-ray beams. The performance of these machines is strongly related to the brightness of the electron beam generating the x-rays. The brightness of the electron beam itself is mainly limited by the physical processes by which electrons are generated. For laser based photoemission sources this limit is ultimately related to the properties of photocathodes. In this paper an overview of the recent progress on photocathode development for photoemission electron sources is presented.

THP192

Effect of Surface Roughness on the Emittance from GaAs Photocathode

2480

S.S. Karkare, I.V. Bazarov
Cornell University, Ithaca, New York, USA
L. Cultrera, A. Iyer, X. Liu, W.J. Schaff
CLASSE, Ithaca, New York, USA

Funding: This work is supported by NSF under Grant No. DMR- 0807731 and DOE under Grant No. DE-SC0003965.
The surface roughness of GaAs photocathodes used in the injector prototype for the ERL at Cornell University was measured and compared to that of the atomically polished GaAs crystal surface using the atomic force microscopy (AFM) technique. The results show at least an order of magnitude rise in the GaAs surface roughness after subjecting it to heat cleaning, prior to activation. An analytical model for photoemission that takes into account the effect of surface roughness has been developed. This model predicts emittance values close to the experimental observations, explains the experimentally observed variation of emittance with incident light wavelength and reconciles the discrepancies in experimental data.

Paper	Title	Page
TUOBS2	Cornell ERL Research and Development	729
	C.E. Mayes, I.V. Bazarov, S.A. Belomestnykh, D.H. Bilderback, M.G. Billing, J.D. Brock, E.P. Chojnacki, J.A. Crittenden, L. Cultrera, J. Dobbins, B.M. Dunham, R.D. Ehrlich, M. P. Ehrlichman, E. Fontes, C.M. Gulliford, D.L. Hartill, G.H. Hoffstaetter, V.O. Kostroun, F.A. Laham, Y. Li, M. Liepe, X. Liu, F. Löhl, A. Meseck, A.A. Mikhailichenko, H. Padamsee, S. Posen, P. Quigley, P. Revesz, D.H. Rice, D. Sagan, V.D. Shemelin, E.N. Smith, K.W. Smolenski, A.B. Temnykh, M. Tigner, N.R.A. Valles, V. Veshcherevich, Y. Xie CLASSE, Ithaca, New York, USA S.S. Karkare, J.M. Maxson Cornell University, Ithaca, New York, USA
	Funding: Supported by NSF award DMR-0807731. Energy Recovery Linacs (ERLs) are proposed as drivers for hard X-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. The advantages of ERL lightsources will be explained, and the status of plans for such facilities will be described. In particular, Cornell University plans to build an ERL light source, and the preparatory research for its construction will be discussed. This will include the prototype injector for high current CW ultra-low emittance beams, superconducting CW technology, the transport of low emittance beams, halo formation from intrabeam scattering, the mitigation of ion effects, the suppression of instabilities, and front to end simulations. Several of these topics could become important for other modern light source projects, such as SASE FELs, HGHG FELs, and XFELOs.
	Slides TUOBS2 [5.632 MB]

WEP244	Growth and Characterization of Bialkali Photocathodes for Cornell ERL Injector	1942
	L. Cultrera, I.V. Bazarov, J.V. Conway, B.M. Dunham, Y. Li, X. Liu, K.W. Smolenski CLASSE, Ithaca, New York, USA S.S. Karkare, J.M. Maxson Cornell University, Ithaca, New York, USA
	The requirements of high quantum efficiency in the visible spectral range and that of an increased lifetime as compared to cesiated GaAs can be met by multi-alkali photocathodes, either CsKSb or NaKSb. In this paper we detail the procedures that allow the growth of thin films suitable for the ERL photoinjector operating at Cornell University. Quantum efficiency, spectral response, and surface characterization of deposited samples is presented. A load-locked multi-alkali cathode growth system is also described.

THOCN1	Cathodes for Photoemission Guns	2099
	L. Cultrera CLASSE, Ithaca, New York, USA
	The last decade has seen a considerable interest in pursuit and realization of novel light sources such as Free Electron Lasers and Energy Recovery Linacs that promise to deliver unprecedented quality x-ray beams. The performance of these machines is strongly related to the brightness of the electron beam generating the x-rays. The brightness of the electron beam itself is mainly limited by the physical processes by which electrons are generated. For laser based photoemission sources this limit is ultimately related to the properties of photocathodes. In this paper an overview of the recent progress on photocathode development for photoemission electron sources is presented.

THP192	Effect of Surface Roughness on the Emittance from GaAs Photocathode	2480
	S.S. Karkare, I.V. Bazarov Cornell University, Ithaca, New York, USA L. Cultrera, A. Iyer, X. Liu, W.J. Schaff CLASSE, Ithaca, New York, USA
	Funding: This work is supported by NSF under Grant No. DMR- 0807731 and DOE under Grant No. DE-SC0003965. The surface roughness of GaAs photocathodes used in the injector prototype for the ERL at Cornell University was measured and compared to that of the atomically polished GaAs crystal surface using the atomic force microscopy (AFM) technique. The results show at least an order of magnitude rise in the GaAs surface roughness after subjecting it to heat cleaning, prior to activation. An analytical model for photoemission that takes into account the effect of surface roughness has been developed. This model predicts emittance values close to the experimental observations, explains the experimentally observed variation of emittance with incident light wavelength and reconciles the discrepancies in experimental data.