The influence of random perturbations of high intensity accelerator elements on the beam losses is
considered. This paper presents the error sensitivity study which has been performed for the SPIRAL2
linac in order to define the tolerances for the construction. The proposed driver aims to accelerate a 5 mA
deuteron beam up to 20 AMeV and a 1 mA ion beam for q/A=1/3 up to 14.5 AMeV. It is a continuous
wave regime linac, designed for a maximum efficiency in the transmission of intense beams and a tunable
energy. It consists in an injector (two ECRs sources + LEBTs with the possibility to inject from
several sources + radio frequency quadrupole) followed by a superconducting section based on an array
of independently phased cavities where the transverse focalization is performed with warm quadrupoles.
The correction scheme and the expected losses are described. The extreme value theory is used to estimate
the expected beam losses. The described method couples large scale computations to obtain probability
distribution functions. The bootstrap technique is used to provide confidence intervals associated to the
beam loss predictions. With such a method, it is possible to measure the risk to loose a few watts in this
high power linac (up to 200 kW). |
