IPAC2012 - List of Authors (Dallin, L.O.)

Paper	Title	Page
MOPPP053	Failure Mode Analysis in Preparation for Top-up Injection at the Canadian Light Source (CLS)	682
	L.O. Dallin CLS, Saskatoon, Saskatchewan, Canada
	Top-up injection involves injecting beam with beamline safety shutters open. Consequently it is extremely important that no electrons enter the beamlines where they could be a potential safety hazard to beamline personnel. To investigate the likelihood that electrons could exit the storage ring various failure mode simulations have been done. The approach is to account for all possible injection trajectories and show that these particles will be intercepted by various storage ring apertures before they reach an amplitude that is deemed unsafe. This amplitude was chosen to be 50 mm and the field roll-off of all storage ring magnets were defined to this amplitude. Failure modes invested included injection kicker failures, uncorrected misalignment errors, off-energy injection and shorted storage ring magnet coils. Errors that would render it impossible to store beam were not investigated. As some particles reached amplitudes beyond the safe limit measures have been devised to eliminate these unsafe scenarios.

MOPPP061	Using RADIA to Model Superconducting Wigglers at the Canadian Light Source	699
	C.K. Baribeau, L.O. Dallin, M.J. Sigrist, W.A. Wurtz CLS, Saskatoon, Saskatchewan, Canada
	The Canadian Light Source operates two superconducting wigglers: a 2 Tesla, 63 pole wiggler, and a 4 Tesla, 27 pole wiggler. Both SCWs have a negative impact on the injection efficiency. Beam based measurements indicate a larger than expected sextupole moment, and the 4T wiggler produces a large horizontal tune shift. To better understand these effects, computer models were developed for the SCWs using the magnetic modelling software package, RADIA. The RADIA models accurately predict the wiggler on-axis field strength and vertical tune shift. By introducing physical misalignments, the models can produce sextupole moments of the same order of magnitude as the measured quantities. However, the modelled horizontal tune shift is orders of magnitude smaller than the 4T wiggler’s observed tune shift. Various model parameters were investigated for their effect on horizontal tune shift, but the cause of the 4T wiggler’s large horizontal tune shift remains unknown.

TUPPP001	Beam Based Measurements with Superconducting Wigglers at the Canadian Light Source with Applications to Nonlinear Beam Dynamics	1599
	W.A. Wurtz, L.O. Dallin, M.J. Sigrist CLS, Saskatoon, Saskatchewan, Canada
	The Canadian Light Source (CLS) employs two superconducting wigglers for the production of hard x-rays. These wigglers cause a large decrease in injection efficiency. While such a decrease is not unexpected due to the large distortion to the linear optics, a correction to the linear optics does not restore injection efficiency. This inability to restore injection is not predicted by a kickmap model of the wiggler. We performed beam based measurements to construct a phenomenological, nonlinear model of the wiggler. Particle tracking with this wiggler model shows that the reduction in dynamic aperture is due to the amplitude dependent tune shift crossing a resonance, even with the linear optics corrected. Moving the tunes allows us to avoid this resonance and measurements at these tunes show that injection efficiency is not greatly affected by the wigglers.

TUPPP002	GLASS Study of the Canadian Light Source Storage Ring Lattice	1602
	W.A. Wurtz, L.O. Dallin CLS, Saskatoon, Saskatchewan, Canada
	GLASS is a technique for finding all potential operating points of a storage ring lattice by examining all possible configurations of the linear lattice. The Canadian Light Source (CLS) storage ring uses three quadrupole families, making it computationally efficient to use GLASS to study the lattice with unbroken symmetry. CLS does not employ harmonic sextupoles and has only two families of chromatic sextupoles. We can exhaust the sextupole degrees of freedom by requiring the horizontal and vertical chromaticities to be both zero. With no remaining free parameters in our lattice, it is possible to calculate dynamic aperture and momentum acceptance for select regions of interest uncovered by the GLASS scan. We find two regions with reasonable dynamic aperture and momentum acceptance: the region where we presently operate and a region that can be accessed by reversing the polarity of one quadrupole family.

Paper

Title

Page

Failure Mode Analysis in Preparation for Top-up Injection at the Canadian Light Source (CLS)

682

L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada

Top-up injection involves injecting beam with beamline safety shutters open. Consequently it is extremely important that no electrons enter the beamlines where they could be a potential safety hazard to beamline personnel. To investigate the likelihood that electrons could exit the storage ring various failure mode simulations have been done. The approach is to account for all possible injection trajectories and show that these particles will be intercepted by various storage ring apertures before they reach an amplitude that is deemed unsafe. This amplitude was chosen to be 50 mm and the field roll-off of all storage ring magnets were defined to this amplitude. Failure modes invested included injection kicker failures, uncorrected misalignment errors, off-energy injection and shorted storage ring magnet coils. Errors that would render it impossible to store beam were not investigated. As some particles reached amplitudes beyond the safe limit measures have been devised to eliminate these unsafe scenarios.

MOPPP061

Using RADIA to Model Superconducting Wigglers at the Canadian Light Source

699

C.K. Baribeau, L.O. Dallin, M.J. Sigrist, W.A. Wurtz
CLS, Saskatoon, Saskatchewan, Canada

The Canadian Light Source operates two superconducting wigglers: a 2 Tesla, 63 pole wiggler, and a 4 Tesla, 27 pole wiggler. Both SCWs have a negative impact on the injection efficiency. Beam based measurements indicate a larger than expected sextupole moment, and the 4T wiggler produces a large horizontal tune shift. To better understand these effects, computer models were developed for the SCWs using the magnetic modelling software package, RADIA. The RADIA models accurately predict the wiggler on-axis field strength and vertical tune shift. By introducing physical misalignments, the models can produce sextupole moments of the same order of magnitude as the measured quantities. However, the modelled horizontal tune shift is orders of magnitude smaller than the 4T wiggler’s observed tune shift. Various model parameters were investigated for their effect on horizontal tune shift, but the cause of the 4T wiggler’s large horizontal tune shift remains unknown.

TUPPP001

Beam Based Measurements with Superconducting Wigglers at the Canadian Light Source with Applications to Nonlinear Beam Dynamics

1599

W.A. Wurtz, L.O. Dallin, M.J. Sigrist
CLS, Saskatoon, Saskatchewan, Canada

The Canadian Light Source (CLS) employs two superconducting wigglers for the production of hard x-rays. These wigglers cause a large decrease in injection efficiency. While such a decrease is not unexpected due to the large distortion to the linear optics, a correction to the linear optics does not restore injection efficiency. This inability to restore injection is not predicted by a kickmap model of the wiggler. We performed beam based measurements to construct a phenomenological, nonlinear model of the wiggler. Particle tracking with this wiggler model shows that the reduction in dynamic aperture is due to the amplitude dependent tune shift crossing a resonance, even with the linear optics corrected. Moving the tunes allows us to avoid this resonance and measurements at these tunes show that injection efficiency is not greatly affected by the wigglers.

TUPPP002

GLASS Study of the Canadian Light Source Storage Ring Lattice

1602

W.A. Wurtz, L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada

GLASS is a technique for finding all potential operating points of a storage ring lattice by examining all possible configurations of the linear lattice. The Canadian Light Source (CLS) storage ring uses three quadrupole families, making it computationally efficient to use GLASS to study the lattice with unbroken symmetry. CLS does not employ harmonic sextupoles and has only two families of chromatic sextupoles. We can exhaust the sextupole degrees of freedom by requiring the horizontal and vertical chromaticities to be both zero. With no remaining free parameters in our lattice, it is possible to calculate dynamic aperture and momentum acceptance for select regions of interest uncovered by the GLASS scan. We find two regions with reasonable dynamic aperture and momentum acceptance: the region where we presently operate and a region that can be accessed by reversing the polarity of one quadrupole family.