No abstract
A fast cycling RF-system glvlng high energy-gain per revolution was required to overcome the intensity limitations set by space-charge in the CERN SC. All other frequency modulation methods being discarded for power reasons, a high Q system tuned by a rotary capacitor was chosen.The rotary capacitor, constituing the most critical part, requires excellent vacuum, forced cooling on all RF electrodes and high mechanical precision. The mechanical problems which, in the early stage of the design, were feared most, proved to be solvable. However, considerable effort was necessary to obtain sufficient reliability of vacuum and cooling circuits. Specially shaped stator blades are used to furnish an optimized frequency modulation programme.The RF circuit design by means of models and computer programmes was initiated at first at CERN and continued later by industry. Detail hardware design and construction was performed by industry, further development and running-in by CERN.The system is performing satisfactorily and has permitted acceleration of the design proton intensity per machine pulse.1. History Excellent results of the new sector-focussed cyc 1 otrons were reported in 1963 at the "Conference on Sector-focussed Cyclotrons and Meson Factori es" concerning intensity, beam quality and extraction efficiency]}. The utilization of mid-plane hooded arc ion sources with high acceleration voltages was essential to achieve this result. The CERN SC magnet did not allow the conversion of the old SC into a sector-focussed fixed frequency machine while keeping the maximum energy unchanged. Therefore a first proposal for a conversion of the SC RF system into a fast cycling system with an acceleration time of 950 ~s, permitting the use of a hooded arc ion source in the SC was made in 1963 2 }3}. Detailed investigations lead to a "Proposal for the Improvement of the 600 MeV Synchrocyclotron,,4}. Because all other frequency modulation methods had to be discarded for power reasons, a high Q system, tuned by a rotary capacitor, was chosen. The design of frequency modulated RF systems has to take account of many limiting circumstances, which become particularly hampering when the maximum proton energy of the cyclotron exceeds several hundred MeV, because mechanical dimensions and necessary frequency swing increase at the same time. A careful system design was necessary to obtain the required frequency range, the frequency-time dependence, the variation range of the lower frequency end and last but not least to keep the RF power consumption and the electrical field strength between the capacitor electrodes within admissible limitsS}. (Fig. l}. Computations were checked at first on a 1:5 scale model, later on a 1:1 model. RF System Design
A digital data acquisition system (DAS) based on a minicomputer is described which registers the failure sequences in various equipment areas of the CERN synchrocyclotron (henceforward referred to as the SC). The avalanches of failure signals which occur from time to time are tapped from the alarm/ security systems, time-resolved to 10 msec and recorded on a printer in order to aid SC failure diagnosis. The mechanisms of the DAS and its relation to the SC equipment are explained in some detail. All programs were constructed at assembler language level for speed and for ease of on-line program maintenance. The alarm sequences recorded have been of considerable help during the running in of the new radiofrequency system. Now that the new SC is operational, the DAS furnishes useful data from several equipment areas to the operators and engineers. IntroductionIt was felt that a better understanding of the series of events occurring upon SC failures than could be obtained with visual failure indicators was necessary in order to decrease the time taken in machine fault-tracing. Some failures happened mysteriously and the sequences of alarms occurring needed to be analysed so as to find the likely source of trouble and get the SC running again as soon as possible.
The design principles and first running experiences of the CERN SC 2 RF beam stretching system are described.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.