PAC2013 - List of Authors (Leemann, S.C.)

Paper	Title	Page
MOPHO05	Coupling and Brightness Considerations for the MAX IV 3 GeV Storage Ring	243
	S.C. Leemann, M. Eriksson MAX-lab, Lund, Sweden
	It is often suggested that the emittance coupling of a storage ring should be adjusted to the so-called diffraction limit corresponding to the shortest wavelength of interest. For 1 A radiation this leads to a typical requirement of 8 pm rad vertical emittance. In ultralow-emittance storage rings like the MAX IV 3 GeV storage ring this corresponds to a comparably large setting of the emittance coupling (2.5%). This approach, however, does not produce the brightest radiation and needs to be revisited taking into account that overall photon brightness depends on the emittances of the electron beam and the intrinsic photon beam. This paper summarizes an analytic approach to maximizing brightness as a function of emittance coupling while retaining sufficient lifetime. Instead of "meeting the diffraction limit", we further reduce the coupling, thus increasing both the brightness and transverse coherence of the emitted radiation. We derive that reducing the MAX IV 3 GeV storage ring's vertical emittance to 2 pm rad (0.6% coupling) will increase brightness and transverse coherence by almost a factor two while 10 h overall lifetime can still be achieved.

TUPMA02	High-Chromaticity Optics for the MAX IV 3 GeV Storage Ring	592
	T. Olsson, S.C. Leemann MAX-lab, Lund, Sweden
	The ultralow emittance lattice of the MAX IV 3 GeV storage ring has a large negative natural chromaticity. This has to be corrected to positive values to prevent head-tail instabilities. On the other hand, high linear chromaticity can lead to a large tune footprint which limits Touschek lifetime. Therefore, the linear chromaticity is corrected to +1 in both planes with sextupoles while octupoles are used to further reduce the tune footprint. Studies indicate this design leads to threshold currents for resistive wall and transverse mode coupling instabilities beyond what is expected during regular user operation. However, since these are only preliminary studies based on approximations, the possibility of instability issues during commissioning needs to be considered. A short term solution is to operate the storage ring at a higher chromaticity. This paper describes the developed high-chromaticity optics for the MAX IV 3 GeV storage ring. It focuses on reduction of chromatic and amplitude-dependent tune shifts to maximize dynamic aperture and Touschek lifetime. A comparison between the performance of the new high-chromaticity optics and the design optics is also presented.

WEPSM05	Progress on Pulsed Multipole Injection for the MAX IV Storage Rings	1052
	S.C. Leemann MAX-lab, Lund, Sweden L.O. Dallin CLS, Saskatoon, Saskatchewan, Canada
	Injection into the MAX IV storage rings will not make use of a conventional local injection bump with four dipole kickers. Instead, pulsed multipole injection will be applied. Previously, it was foreseen to use a pulsed sextupole magnet similar to what KEK had originally designed for the PF ring. But after seeing encouraging results with a prototype nonlinear kicker magnet developed for BESSY II, pulsed multipole injection for the MAX IV storage rings was revisited. A nonlinear kicker magnet similar to the BESSY-type can be realized for both MAX IV storage rings. Such a nonlinear kicker offers a broad zero-field region around the center which does not perturb the stored beam, while offering a high-field region around the location of the injected beam making it ideal for top-up injection. This paper summarizes the proposed kicker magnet design and shows beam dynamics results from multi-particle tracking studies. A comparison with the previous PSM design is also included.

Paper

Title

Page

Coupling and Brightness Considerations for the MAX IV 3 GeV Storage Ring

243

S.C. Leemann, M. Eriksson
MAX-lab, Lund, Sweden

It is often suggested that the emittance coupling of a storage ring should be adjusted to the so-called diffraction limit corresponding to the shortest wavelength of interest. For 1 A radiation this leads to a typical requirement of 8 pm rad vertical emittance. In ultralow-emittance storage rings like the MAX IV 3 GeV storage ring this corresponds to a comparably large setting of the emittance coupling (2.5%). This approach, however, does not produce the brightest radiation and needs to be revisited taking into account that overall photon brightness depends on the emittances of the electron beam and the intrinsic photon beam. This paper summarizes an analytic approach to maximizing brightness as a function of emittance coupling while retaining sufficient lifetime. Instead of "meeting the diffraction limit", we further reduce the coupling, thus increasing both the brightness and transverse coherence of the emitted radiation. We derive that reducing the MAX IV 3 GeV storage ring's vertical emittance to 2 pm rad (0.6% coupling) will increase brightness and transverse coherence by almost a factor two while 10 h overall lifetime can still be achieved.

TUPMA02

High-Chromaticity Optics for the MAX IV 3 GeV Storage Ring

592

T. Olsson, S.C. Leemann
MAX-lab, Lund, Sweden

The ultralow emittance lattice of the MAX IV 3 GeV storage ring has a large negative natural chromaticity. This has to be corrected to positive values to prevent head-tail instabilities. On the other hand, high linear chromaticity can lead to a large tune footprint which limits Touschek lifetime. Therefore, the linear chromaticity is corrected to +1 in both planes with sextupoles while octupoles are used to further reduce the tune footprint. Studies indicate this design leads to threshold currents for resistive wall and transverse mode coupling instabilities beyond what is expected during regular user operation. However, since these are only preliminary studies based on approximations, the possibility of instability issues during commissioning needs to be considered. A short term solution is to operate the storage ring at a higher chromaticity. This paper describes the developed high-chromaticity optics for the MAX IV 3 GeV storage ring. It focuses on reduction of chromatic and amplitude-dependent tune shifts to maximize dynamic aperture and Touschek lifetime. A comparison between the performance of the new high-chromaticity optics and the design optics is also presented.

WEPSM05

Progress on Pulsed Multipole Injection for the MAX IV Storage Rings

1052

S.C. Leemann
MAX-lab, Lund, Sweden
L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada

Injection into the MAX IV storage rings will not make use of a conventional local injection bump with four dipole kickers. Instead, pulsed multipole injection will be applied. Previously, it was foreseen to use a pulsed sextupole magnet similar to what KEK had originally designed for the PF ring. But after seeing encouraging results with a prototype nonlinear kicker magnet developed for BESSY II, pulsed multipole injection for the MAX IV storage rings was revisited. A nonlinear kicker magnet similar to the BESSY-type can be realized for both MAX IV storage rings. Such a nonlinear kicker offers a broad zero-field region around the center which does not perturb the stored beam, while offering a high-field region around the location of the injected beam making it ideal for top-up injection. This paper summarizes the proposed kicker magnet design and shows beam dynamics results from multi-particle tracking studies. A comparison with the previous PSM design is also included.