FEL2014 - List of Authors (Dunham, B.M.)

Paper	Title	Page
THP042	The LCLS-II Injector Design	815
	J.F. Schmerge, A. Brachmann, D. Dowell, A.R. Fry, R.K. Li, Z. Li, T.O. Raubenheimer, T. Vecchione, F. Zhou SLAC, Menlo Park, California, USA A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA D. Filippetto, R. Huang, C. F. Papadopoulos, G.J. Portmann, J. Qiang, F. Sannibale, S.P. Virostek, R.P. Wells LBNL, Berkeley, California, USA A. Lunin, N. Solyak, A. Vivoli Fermilab, Batavia, Illinois, USA
	The new LCLS-II project will construct a 4 GeV continuous wave (CW) superconducting linear accelerator to simultaneously feed two undulators which will cover the spectral ranges 0.2-1.2 keV and 1-5 keV, respectively. The injector must provide up to 300 pC/bunch with a normalized emittance < 0.6 mm and peak current > 30 A at up to 1 MHz repetition rate. An electron gun with the required brightness at such high repetition rate has not yet been demonstrated. However, several different options have been explored with results that meet or exceed the performance requirements of LCLS-II. The available technologies for high repetition-rate guns, and the need to keep dark current within acceptable values, limit the accelerating gradient in the electron gun. We propose a CW normal conducting low frequency RF gun for the electron source due to a combination of the simplicity of operation and the highest achieved gradient in a CW gun, potentially allowing for lower beam emittances. The high gradient is especially significant at the 300 pC/bunch charge where beam quality can suffer due to space charge. This paper describes the design challenges and presents our solutions for the LCLS-II injector.

THP057	Longitudinal and Transverse Optimization for a High Repetition Rate Injector	864
	C. F. Papadopoulos, D. Filippetto, R. Huang, G.J. Portmann, H.J. Qian, F. Sannibale, S.P. Virostek, R.P. Wells LBNL, Berkeley, California, USA A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A. Brachmann, D. Dowell, P. Emma, Z. Li, T.O. Raubenheimer, J.F. Schmerge, T. Vecchione, F. Zhou SLAC, Menlo Park, California, USA A. Vivoli Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 The injector is the low energy part of a linac, where space charge and kinematic effects may affect the electron beam quality significantly, and in the case of single pass systems determines the brightness in the downstream components. Following the increasing demand for high repetition rate user facilities, the VHF-gun, a normal conducting, high repetition rate (1 MHz) RF gun operating at 186 MHz has been constructed at LBNL within the APEX project and is under operation. In the current paper, we report on the status of the beam dynamics studies. For this, a multi-objected approach is used, where both the transverse and the longitudinal phase space quality is optimized, as quantified by the transverse emittance and the bunch length and energy spread respectively. We also report on different bunch charge operating modes.

Paper

Title

Page

The LCLS-II Injector Design

815

J.F. Schmerge, A. Brachmann, D. Dowell, A.R. Fry, R.K. Li, Z. Li, T.O. Raubenheimer, T. Vecchione, F. Zhou
SLAC, Menlo Park, California, USA
A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D. Filippetto, R. Huang, C. F. Papadopoulos, G.J. Portmann, J. Qiang, F. Sannibale, S.P. Virostek, R.P. Wells
LBNL, Berkeley, California, USA
A. Lunin, N. Solyak, A. Vivoli
Fermilab, Batavia, Illinois, USA

The new LCLS-II project will construct a 4 GeV continuous wave (CW) superconducting linear accelerator to simultaneously feed two undulators which will cover the spectral ranges 0.2-1.2 keV and 1-5 keV, respectively. The injector must provide up to 300 pC/bunch with a normalized emittance < 0.6 mm and peak current > 30 A at up to 1 MHz repetition rate. An electron gun with the required brightness at such high repetition rate has not yet been demonstrated. However, several different options have been explored with results that meet or exceed the performance requirements of LCLS-II. The available technologies for high repetition-rate guns, and the need to keep dark current within acceptable values, limit the accelerating gradient in the electron gun. We propose a CW normal conducting low frequency RF gun for the electron source due to a combination of the simplicity of operation and the highest achieved gradient in a CW gun, potentially allowing for lower beam emittances. The high gradient is especially significant at the 300 pC/bunch charge where beam quality can suffer due to space charge. This paper describes the design challenges and presents our solutions for the LCLS-II injector.

THP057

Longitudinal and Transverse Optimization for a High Repetition Rate Injector

864

C. F. Papadopoulos, D. Filippetto, R. Huang, G.J. Portmann, H.J. Qian, F. Sannibale, S.P. Virostek, R.P. Wells
LBNL, Berkeley, California, USA
A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A. Brachmann, D. Dowell, P. Emma, Z. Li, T.O. Raubenheimer, J.F. Schmerge, T. Vecchione, F. Zhou
SLAC, Menlo Park, California, USA
A. Vivoli
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The injector is the low energy part of a linac, where space charge and kinematic effects may affect the electron beam quality significantly, and in the case of single pass systems determines the brightness in the downstream components. Following the increasing demand for high repetition rate user facilities, the VHF-gun, a normal conducting, high repetition rate (1 MHz) RF gun operating at 186 MHz has been constructed at LBNL within the APEX project and is under operation. In the current paper, we report on the status of the beam dynamics studies. For this, a multi-objected approach is used, where both the transverse and the longitudinal phase space quality is optimized, as quantified by the transverse emittance and the bunch length and energy spread respectively. We also report on different bunch charge operating modes.