Frequency Tunable 4-rod RFQ
Yoshihisa Iwashita and Hiroshi Fujisawa*
Accelerator Laboratory, Nuclear Science Facility
Institute for Chemical Research, Kyoto University
Gokanosho, Uji-shi, Kyoto-fu 611 Japan
*R&D Division, Nissin Electric Co.,Ltd.
575 Kuze Tonoshiro-cho, Minami-ku, Kyoto-shi, Kyoto-fu 601 Japan
The frequency tunability of the 4-rod RFQ is investigated. The experimental
results show that the resonant frequency can be varied almost twofold by
moving the shorting electrodes between the posts, which support the 4-rod electrodes
from the base. In that configuration the shunt impedance is found to be low at
higher frequency region. An additional ON-OFF posts-shorting electrode above the
electrodes can overcome this draw back. It raises the resonant frequency without
lowering the shunt impedance too much and when used with the moving
shorting-plates it expands practically available resonant frequency range.
Because the ON-OFF shorting electrode requires no sliding rf contact, this
device is simple and easy to fabricate. The effect of the proposed ON-OFF
shorting electrode is studied by MAFIA.
Here is the PostScript document.