Abstract

We demonstrated a new injection scheme using a single pulsed quadrupole magnet (PQM) with no pulsed local bump at the Photon Factory Advanced Ring (PF-AR) in High Energy Accelerator Research Organization (KEK). The scheme employs the basic property of a quadrupole magnet, that the field at the center is zero, and nonzero elsewhere. The amplitude of coherent betatron oscillation of the injected beam is effectively reduced by the PQM; then, the injected beam is captured into the ring without largely affecting the already stored beam. In order to investigate the performance of the scheme with a real beam, we built the PQM providing a higher field gradient over $3\text{ }\text{ }\mathrm{T}/\mathrm{m}$ and a shorter pulse width of $2.4\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$, which is twice the revolution period of the PF-AR. After the field measurements confirmed the PQM specifications, we installed it into the ring. Then, we conducted the experiment using a real beam and consequently succeeded in storing the beam current of more than 60 mA at the PF-AR. This is the first successful beam injection using a single PQM in electron storage rings.

Highlights

  • In a conventional injection scheme for electron storage rings such as synchrotron light sources or electron-positron colliders, several pulsed dipole magnets, which are called kicker magnets, are employed to reduce the effective amplitude of the injected beam and facilitate beam injection while preserving an already stored beam [1]

  • The stored beam with the equilibrium emittance passes a pulsed local bump, which is formed by the kickers around the injection point; the beam preserves its central orbit in other parts of the ring

  • When the transverse and/or the longitudinal instabilities are generated by the rf cavities at a higher beam current and the horizontal beam size increases, a part of the stored beam is lost at the vacuum chamber around the injection point due to the pulsed bump

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Summary

INTRODUCTION

In a conventional injection scheme for electron storage rings such as synchrotron light sources or electron-positron colliders, several pulsed dipole magnets, which are called kicker magnets, are employed to reduce the effective amplitude of the injected beam and facilitate beam injection while preserving an already stored beam [1]. The stored beam with the equilibrium emittance passes a pulsed local bump, which is formed by the kickers around the injection point; the beam preserves its central orbit in other parts of the ring. When the transverse and/or the longitudinal instabilities are generated by the rf cavities at a higher beam current and the horizontal beam size increases, a part of the stored beam is lost at the vacuum chamber around the injection point due to the pulsed bump. We report the experimental result using a real beam

Conventional injection scheme using a pulsed local bump
Injection scheme using a single PQM
Application to the PF-AR
For the injected beam
For the stored beam
Pulsed quadrupole magnet
Pulsed power supply
Ceramic chamber
Field measurements
Z peak
EXPERIMENTAL RESULT USING A REAL
CONCLUSION
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