FEL2013 - List of Authors (Kim, K.-J.)

Paper

Title

Page

Transverse Gradient Undulators for a Storage Ring X-ray FEL Oscillator

740

R.R. Lindberg, K.-J. Kim
ANL, Argonne, USA
Y. Cai, Y. Ding, Z. Huang
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Dept.~of Energy, Office of Basic Energy Sciences, Contract No.~DE-AC02-06CH11357.
An x-ray FEL oscillator (XFELO) is a fully coherent 4th generation source with complementary scientific applications to those based on self-amplified spontaneous emission*. While the naturally high repetition rate, intrinsic stability, and very small emittance produced by an ultimate storage ring (USR) makes it a potential candidate to drive an XFELO, the energy spread is typically an order of magnitude too large for sufficient gain. On the other hand, Smith and coworkers** showed how the energy spread requirement can be effectively mitigated with a transverse gradient undulator (TGU): since the TGU has a field strength that varies with transverse position, by properly correlating the electron energy with transverse position one can approximately satisfy the FEL resonance condition for all electrons. Motivated by recent work in the high-gain regime***, we investigate the utility of a TGU for low gain FELs at x-ray wavelengths. We find that a TGU may make an XFELO realizable in the largest ultimate storage rings now under consideration (e.g., in either the old Tevatron or PEP-II tunnel).
* K.-J. Kim, Y. Shvyd'ko and S. Reiche, PRL 100 244802 (2008).
** T. Smith, et al., J. Appl. Phys. 50, 4580 (1979).
*** Z. Huang, Y. Ding, and C.B. Schroeder, PRL 109, 204801 (2012).

Slides THOBNO02 [1.208 MB]

Paper	Title	Page
THOBNO02	Transverse Gradient Undulators for a Storage Ring X-ray FEL Oscillator	740
	R.R. Lindberg, K.-J. Kim ANL, Argonne, USA Y. Cai, Y. Ding, Z. Huang SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Dept.~of Energy, Office of Basic Energy Sciences, Contract No.~DE-AC02-06CH11357. An x-ray FEL oscillator (XFELO) is a fully coherent 4th generation source with complementary scientific applications to those based on self-amplified spontaneous emission. While the naturally high repetition rate, intrinsic stability, and very small emittance produced by an ultimate storage ring (USR) makes it a potential candidate to drive an XFELO, the energy spread is typically an order of magnitude too large for sufficient gain. On the other hand, Smith and coworkers* showed how the energy spread requirement can be effectively mitigated with a transverse gradient undulator (TGU): since the TGU has a field strength that varies with transverse position, by properly correlating the electron energy with transverse position one can approximately satisfy the FEL resonance condition for all electrons. Motivated by recent work in the high-gain regime**, we investigate the utility of a TGU for low gain FELs at x-ray wavelengths. We find that a TGU may make an XFELO realizable in the largest ultimate storage rings now under consideration (e.g., in either the old Tevatron or PEP-II tunnel). K.-J. Kim, Y. Shvyd'ko and S. Reiche, PRL 100 244802 (2008). T. Smith, et al., J. Appl. Phys. 50, 4580 (1979). * Z. Huang, Y. Ding, and C.B. Schroeder, PRL 109, 204801 (2012).
	Slides THOBNO02 [1.208 MB]