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Interplay of Touschek scattering, intrabeam scattering, and rf cavities in ultralow-emittance storage rings

Leemann, Simon LU (2014) In Physical Review Special Topics. Accelerators and Beams 17(5). p.7-050705
Abstract
The latest generation of storage ring-based light sources employs multibend achromat lattices to achieve ultralow emittance. These lattices make use of a large number of weak bending magnets which considerably reduces the amount of power radiated in the dipoles in comparison to power radiated from insertion devices. Therefore, in such storage rings, parameters such as emittance, energy spread, and radiated power are—unlike 3rd generation storage rings—no longer constant during a typical user shift. Instead, they depend on several varying parameters such as insertion device gap settings, bunch charge, bunch length, etc. Since the charge per bunch is usually high, intrabeam scattering in medium-energy storage rings with ultralow emittance... (More)
The latest generation of storage ring-based light sources employs multibend achromat lattices to achieve ultralow emittance. These lattices make use of a large number of weak bending magnets which considerably reduces the amount of power radiated in the dipoles in comparison to power radiated from insertion devices. Therefore, in such storage rings, parameters such as emittance, energy spread, and radiated power are—unlike 3rd generation storage rings—no longer constant during a typical user shift. Instead, they depend on several varying parameters such as insertion device gap settings, bunch charge, bunch length, etc. Since the charge per bunch is usually high, intrabeam scattering in medium-energy storage rings with ultralow emittance becomes very strong. This creates a dependence of emittance on stored current. Furthermore, since the bunch length is adjusted with rf cavities but is also varied as insertion device gaps change, the emittance blowup from intrabeam scattering is not constant either. Therefore, the emittance, bunch length, and hence the resulting Touschek lifetime have to be calculated in a self-consistent fashion with 6D tracking taking into account not only the bare lattice and rf cavity settings, but also momentary bunch charge and gap settings. Using the MAX IV 3 GeV storage ring as an example, this paper demonstrates the intricate interplay between transverse emittance (insertion devices, emittance coupling), longitudinal emittance (tuning of main cavities as well as harmonic cavities), and choice of stored current in an ultralow-emittance storage ring as well as some implications for brightness optimization. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review Special Topics. Accelerators and Beams
volume
17
issue
5
pages
7 - 050705
publisher
American Physical Society
external identifiers
  • wos:000336654500003
  • scopus:84902089723
ISSN
1098-4402
DOI
10.1103/PhysRevSTAB.17.050705
language
English
LU publication?
yes
id
0f86e0ad-dab3-4d41-b01d-abc1cfdadd2b (old id 4456232)
alternative location
http://journals.aps.org/prstab/abstract/10.1103/PhysRevSTAB.17.050705
date added to LUP
2014-06-04 22:03:34
date last changed
2017-07-09 04:11:51
@article{0f86e0ad-dab3-4d41-b01d-abc1cfdadd2b,
  abstract     = {The latest generation of storage ring-based light sources employs multibend achromat lattices to achieve ultralow emittance. These lattices make use of a large number of weak bending magnets which considerably reduces the amount of power radiated in the dipoles in comparison to power radiated from insertion devices. Therefore, in such storage rings, parameters such as emittance, energy spread, and radiated power are—unlike 3rd generation storage rings—no longer constant during a typical user shift. Instead, they depend on several varying parameters such as insertion device gap settings, bunch charge, bunch length, etc. Since the charge per bunch is usually high, intrabeam scattering in medium-energy storage rings with ultralow emittance becomes very strong. This creates a dependence of emittance on stored current. Furthermore, since the bunch length is adjusted with rf cavities but is also varied as insertion device gaps change, the emittance blowup from intrabeam scattering is not constant either. Therefore, the emittance, bunch length, and hence the resulting Touschek lifetime have to be calculated in a self-consistent fashion with 6D tracking taking into account not only the bare lattice and rf cavity settings, but also momentary bunch charge and gap settings. Using the MAX IV 3 GeV storage ring as an example, this paper demonstrates the intricate interplay between transverse emittance (insertion devices, emittance coupling), longitudinal emittance (tuning of main cavities as well as harmonic cavities), and choice of stored current in an ultralow-emittance storage ring as well as some implications for brightness optimization.},
  author       = {Leemann, Simon},
  issn         = {1098-4402},
  language     = {eng},
  number       = {5},
  pages        = {7--050705},
  publisher    = {American Physical Society},
  series       = {Physical Review Special Topics. Accelerators and Beams},
  title        = {Interplay of Touschek scattering, intrabeam scattering, and rf cavities in ultralow-emittance storage rings},
  url          = {http://dx.doi.org/10.1103/PhysRevSTAB.17.050705},
  volume       = {17},
  year         = {2014},
}