Investigation of a Modified Helix Loaded Superconducting Resonator for Acceleration of Heavy Ions

Abstract

A modified helix loaded cavity was developed. The design is a compromise between a rather simple construction, rigidity and small size on one hand and a reasonably good acceleration of low velocity ions on the other hand. It contains a tapered helix to reduce the ratio of peak electric to effective accelerating field to -7.1 at an optimum relative charged particle velocity of 6 = 0.092. Field measurements at room temperature have been performed as well as first measurements at 4.2 K. The rigidity of the helix was increased resulting in a typical frequency noise smaller ± 175HZpeak at the fundamental frequency of 142 MHz. The design accelerating field is 2.25 MV/m at a peak electric field of 16 MV/m leading to an optimum accelerating potential of 538 kV. In laboratory test measurements an effective accelerating field of 2.36 MV/m was achieved. This corresponds to an accelerating potential of 566 kV at a peak electric surface field of -17 MV/m.

Cavité supraconductrice à hélice pour l'accélération d'ions lourds

“…longueur développée de l'hélice [17], ce qui nous a permis de modifier ce paramètre jusqu'à obtenir un ensemble (hélice soudée dans l'enceinte) résonnant à 81 MHz ± 100 KHz. L'avantage principal des cavités à deux espaces accélérateurs par rapport aux cavités à trois espaces accélérateurs ou plus [18,19] est d'élargir l'acceptance en vitesse de la structure. (AW.a,, = 535 keV pour j6 = 0,085).…”