Longitudinal injection scheme using short pulse kicker for small aperture electron storage rings

Abstract

Future light sources aim at achieving a diffraction limited photon beam both in the horizontal and vertical planes. High gradient quadrupoles and strong chromaticity correction sextupoles in a corresponding ultra-low emittance ring may restrict the physical and dynamic aperture of the storage ring such that offaxis injection and accumulation may become impossible. We propose a longitudinal injection scheme, i.e., injecting an electron bunch onto the closed orbit with a time offset with respect to the circulating bunches. The temporal separation enables a pulsed dipole kicker to situate the injected bunch transversely on-axis without disturbing the circulating bunches if the pulse length is shorter than the bunch spacing. The injected bunch is finally merged to a circulating bunch through synchrotron radiation damping. We present the scheme in detail and its application to the lattice of the MAX IV 3 GeV storage ring. The requirements and feasibility of the pulsed dipole kicker are also discussed.

Injection scheme with deflecting cavity for a fourth-generation storage ring

“…1, red line). Previous longitudinal injection scheme [11] in injects a beam longitudinally at phase -π. In this scheme, the injected bunch then longitudinally damps to the synchrotron phase after injection.…”

“…Previous longitudinal injection scheme [11] needs (1) a kicker that injects a short pulse (a few nanoseconds) so that stored beam is not disturbed, and (2) tight energy jitter and small energy spread of injected beam so that injected beam is put within the acceptance of the longitudinal phase space at the phase -π. To overcome these stringent requirements, a new on-axis injection scheme with two transverse deflecting cavities is suggested ( Fig.…”

Future High Energy Circular Colliders

“…Promising options to realize this top up include conventional off-momentum injection and multipole-kicker injection [32,33]. Figure 10 presents one possible FCC-ee collider layout compatible with the geometry of the hadron collider FCC-hh, which features two collision points at opposite positions of the ring.…”

Using a double-frequency RF system to facilitate on-axis beam accumulation in a storage ring

“…The energy oscillation of the injected bunches in this process can be controlled to less than 1%. This injection scheme will be more tolerate to the energy jitter of the injected beam and the beam dynamics will be more controllable comparing to the scheme proposed in [16].…”

“…While for swap-out without an AR, it requires an injector capable of producing high and stable charged single bunch, also the scheme will get unfavorable radiation dose from the dumped beams. Recently, a novel longitudinal on-axis injection scheme has been proposed in [16], in which a low frequency RF system is used, the bunch is on-axis injected at the RF phase far away from the synchrotron phase with energy slightly higher than the stored beam. Then the injected bunch longitudinal damps to the synchrotron phase.…”