HB2018 - List of Authors (Hofmann, I.)

Paper	Title	Page
THP2WB01	Revisiting the Longitudinal 90 Degree Limit for Superconducting Linear Accelerators	369
	I. Hofmann GSI, Darmstadt, Germany I. Hofmann TEMF, TU Darmstadt, Darmstadt, Germany
	In the design of high-intensity linear accelerators one of the generally adopted criteria is not to exceed a zero-current phase advance per focusing period of 90 degrees in order to avoid the space charge driven envelope instability, or a coinciding fourth order space charge resonance. Recently it was claimed that in certain structures, predominantly applicable to super-conducting linac lattices - such a constraint is not always necessary in the longitudinal plane (I. Hofmann and O. Boine-Frankenheim, Phys. Rev. Lett. 118, 2017). This applies primarily to such focusing structures, where the transverse focusing period only induces a weak space charge dependent modulation in the longitudinal plane, and a different periodicity is applicable to the longitudinal plane. Hence the longitudinal 90 degree stopband is practically absent, and phase advances significantly above 90 degrees should be possible in such structures, with a corresponding additional design freedom. As a consequence, we suggest that the 90 degree rule should no longer be taken as standard criterion in the longitudinal plane of linac design.
	Slides THP2WB01 [5.179 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB01
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Revisiting the Longitudinal 90 Degree Limit for Superconducting Linear Accelerators

369

I. Hofmann
GSI, Darmstadt, Germany
I. Hofmann
TEMF, TU Darmstadt, Darmstadt, Germany

In the design of high-intensity linear accelerators one of the generally adopted criteria is not to exceed a zero-current phase advance per focusing period of 90 degrees in order to avoid the space charge driven envelope instability, or a coinciding fourth order space charge resonance. Recently it was claimed that in certain structures, predominantly applicable to super-conducting linac lattices - such a constraint is not always necessary in the longitudinal plane (I. Hofmann and O. Boine-Frankenheim, Phys. Rev. Lett. 118, 2017). This applies primarily to such focusing structures, where the transverse focusing period only induces a weak space charge dependent modulation in the longitudinal plane, and a different periodicity is applicable to the longitudinal plane. Hence the longitudinal 90 degree stopband is practically absent, and phase advances significantly above 90 degrees should be possible in such structures, with a corresponding additional design freedom. As a consequence, we suggest that the 90 degree rule should no longer be taken as standard criterion in the longitudinal plane of linac design.

Slides THP2WB01 [5.179 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB01

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)