TRANSIENT STATE IN STANDING-WAVE ACCELERATING STRUCTURES

Superconducting accelerating cavities can be operated in the pulse mod e to lower capital and operating costs of the cryogenic plant. Some ad ditional cost reduction is also possible when the accelerating process takes place already during the fill time, i.e. before the acceleratin g structures reach the final steady state. Such an operation needs mor e analysis of the transient state in multicell cavities. In this paper one possible approach to the complete analysis of the transient state in standing wave accelerating structures is presented. The different approach, giving envelope of the transient state, the reader can find in.(1) In this paper set of equations derived from a lumped element re placement circuit model used for the analysis, is solved in a semi-ana lytic way. The method of solution is based on the classical Laplace tr ansformation aided by some additional numerical calculations. The comp uted cavity response to the harmonic driving source agrees well with m easurements for various types of cavities. As an example, comparison o f the transient state measurements and calculations for a 9-cell, 1GHz copper cavity are discussed in more detail. Next, diagrams relating c avity parameters to the time delay al the beginning of the fill and to the phase deviation for the steady state, computed with a program wri tten especially for this analysis are given. Finally, some preliminary computations for structure of the future superconducting linear colli der TESLA are discussed.