BARC, Trombay, Mumbai
Indian Institute of Technology Bombay, Mumbai
TIFR, Mumbai
As a first step towards development in digital domain, a computer model of a self excited loop (SEL) has been created using MATLAB/SIMULINK. The behaviour of a resonator and a power amplifier combination has been approximated using two first-order differential equations. The square of the amplitude of the RF field in the resonator acts as a driving force for the motion of mechanical modes of the resonator, which are individually represented as second order systems. A key element is the limiter, which has been modelled as a feedback loop, to achieve constant output amplitude. The model has been created in the I-Q domain for computational efficiency and close correspondence with actual implementation. To study the field stabilisation, proportional amplitude and phase feedback loops have been appended to the model of the SEL. In this paper we discuss the details of the model and results from simulation. Initial experimental results are also presented.
BARC, Trombay, Mumbai
Indian Institute of Technology Bombay, Mumbai
CERN, Geneva
An RF system model has been created for the CERN Linac2 Tanks. RF systems in this linac have both single and double feed architectures. The main elements of these systems are: RF power amplifier, main resonator, feed-line and the amplitude and phase feedback loops. The model of the composite system is derived by suitably concatenating the models of these individual sub-systems. For computational efficiency the modeling has been carried out in the base band. The signals are expressed in in-phase - quadrature domain, where the response of the resonator is expressed using two linear differential equations, making it valid for large signal conditions. MATLAB/SIMULINK has been used for creating the model. The model has been found useful in predicting the system behaviour, especially during the transients. In the paper we present the details of the model, highlighting the methodology, which could be easily extended to multiple feed RF systems.