DETUNED PRIMARY RF COUPLING SYSTEM FOR VARIABLE FREQUENCY CYCLOTRONS

A new concept of impedance matching for an RF amplifier coupled to a c yclotron cavity, named ''detuned primary coupling'', is proposed. It d oes not require the motion of the coupling loop in vacuum and the matc hing for different working frequencies is performed by ''detuning'' th e eigenfrequency of the amplifier cabinet alone by means of a variable capacitor. A simple mathematical approach used in the design procedur e is presented. Measurements on the 1 : 1 scale model of the VINCY cyc lotron RF system have been carried out in the operating frequencies ra nge. The results confirm the viability of the concept and the use of t his approach in cyclotron RF amplifier coupling. (C) 1998 Elsevier Sci ence B.V. All rights reserved.