Travelling Wave Kicker Research Articles

A Novel Non-Linear Strip-Line Kicker Driven by Fast Pulser in Common Mode

The next generation storage ring-based light sources adopt multi-bend achromat lattices to achieve a low emittance. The dynamic apertures of these machines are usually less than 10 mm so that the traditional pulsed local bump injection is difficult to achieve. Off-axis injection with a pulsed multipole or a non-linear kicker could be a viable solution which requires a moderate dynamic aperture of a few mm. In this paper, a novel non-linear kicker design is presented. Unlike pulsed sextupole or nonlinear kicker magnet, the nonlinear kicker we proposed is a traveling wave kicker with 2 strip-line electrodes driven by a nanosecond-level fast pulser in common mode. The disturbance to the stored beam is minimal since the perturbation is limited to the target bunch alone.

Design of the beam transport line and injection system of the compact storage ring for TTX

In this article, we present the design of the beam transport line and injection system of the compact storage ring for the Tsinghua Thomson scattering X-ray (TTX) source. The layout of the beam transport line fits in with the limited available space. The injection system is simplified, consisting of only one single kicker; the stray field on the reference orbit is also reduced without the septum magnet. We choose a travelling wave kicker and present both 2D and 3D simulations for the structure design.

Improved analytical model of the transverse coupling impedance of ferrite kicker magnets

A transformer model of ferrite kicker magnets is presented in this paper. Based on this model, an equivalent circuit is derived for which the elements can be obtained by bench measurements or by estimates from the magnet geometry. Improved formulas for the transverse coupling impedance of lumped and traveling wave kicker magnets are derived from the model and the equivalent circuit. The formulas differ from the corresponding handbook results in their dependence on the external termination or aperture aspect, respectively. The effect of ferrite properties on the transverse coupling impedance is analyzed. The model was confirmed by bench measurements with the twin-wire technique made on the full-size and half-size prototypes of the extraction kicker of the SNS accumulator ring. The application of this model to the design of the kickers allowed a significant reduction of the SNS transverse coupling impedance budget.

Travelling Wave Kicker Magnets with Sharp Rise and Less Overshoot

As an alternative to the classical design of travelling wave kicker magnets, a structure with a fairly simple additional feature was developed and investigated. This modification was based on the following considerations. The shape of the rise of the magnetic field in a travelling wave kicker is determined by two main factors: i) the shape of the applied current pulse, and ii) the propagation characteristics of the magnet structure. In the PSB kicker system1), kiloampere pulses with a rise-time of ~ 10 ns are obtained by means of ferriteloaded pulse steepening lines2). Measurements show, however, that pulses with this rise-time are severely distorted as they travel along the various kicker magnets. It was therefore thought worth while to examine whether any improvements might be possible, other than the classical remedies of increasing the number of cells or raising the characteristic impedance. To this end a typical magnet module (Fig. 1) was measured using RF techniques and its dispersion curve compared to calculations for various possible equivalent circuits. After concluding that the mutual inductance between cells was a dominant factor, the kicker was modified by adding inductive coupling of opposite sign. This considerably improved the dispersion curve, with a corresponding increase in the phase and group velocities for high frequencies. Although attenuation still produces some distortion, pulse measurements confirmed that the pulse transmission was substantially improved.