Design, test, and operation of new tapered stripline injection kickers for thee+e−colliderDAΦNE

Abstract

For the injection upgrade of the È factory DAÈNE, new fast stripline kickers have been designed. They can operate with very short pulse generators to perturb only the injected bunch and the two stored adjacent ones. The design is based on tapering the striplines to simultaneously obtain low beam coupling and transfer impedances, excellent uniformity of the deflecting field, and better matching between the strip and the pulse generators. It has been done using 2D and 3D electromagnetic codes (SUPERFISH and HFSS). The kickers have been constructed, tested, and installed in the collider. Measurements of the reflection coefficient at input ports and of the longitudinal and transverse beam coupling impedance have been also performed to characterize the structure and have been compared to the simulation results. A circuital model of general tapered striplines for a first order estimation of the transfer and longitudinal beam coupling impedances is also presented. Finally operational performances are described, pointing out the problems which occurred and the flexibility of the stripline structures that worked with both the short and with the previously installed long pulse generators and have been used as an additional damping kicker to improve the efficiency of the horizontal multibunch feedback system. This system is also a demonstration of the operation of fast kickers with similar characteristics as those for the International Linear Collider (ILC) damping rings (DRs).

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

“…[15] in terms of both pulse duration and voltage, we conclude that the kicker required for the MAX IV application is feasible.…”

“…The measured values in Ref. [15] are 0.5 ns and 2 ns, respectively. These values result in a smaller deflecting angle for the 0.75 m long kicker (−25%) than with an ideal rectangular input pulse.…”

“…There are a few strip-line type kickers in operation whose pulse lengths are short enough for the required pulse length of < 10 ns [14,15]. Therefore we assume here the same technology for our kicker.…”

“…In other words, a higher pulser voltage (45.2 kV) is required to achieve the required kick angle. The coverage angle may be varied along the kicker (tapering) to minimize the kicker beam impedance and the reflections at the pulse generator input ports [15]. This also increases the required pulser voltage because of the reduced strip-line impedance.…”

Multibunch beam extraction using the strip-line kicker at the KEK Accelerator Test Facility

“…In work at the accelerator test facility damping ring (ATF DR) in the High Energy Accelerator Research Organization, Naito et al have already tested a single strip-line kicker using a high-voltage semiconductor pulse source and measured the rise/fall time of the beam kick field [3,4]. Grishanov et al, meanwhile, have already proposed a strip-line kicker using a single unit for TESLA [5], and Alesini et al have developed a tapered strip line for the injection of DAÈNE [6]. Their designs and results provide useful information for our own work.…”