The European Spallation Source (ESS) is a joint European project. ESS will be a world-leading centre for materials research and life science with neutrons and will host the World’s most powerful neutron source. A superconducting LINAC will be required to accelerate proton beams at energy levels up-to 2.5 GeV. About 200 klystrons will be required which will be supplied individually by pulsed modulators of the solid state type. The nominal parameters for the initial test stand prototype are -115kV/21A, 3.5ms/14Hz.
The state of the art of solid state pulsed klystron modulators suited for long pulse applications (>100 µs) is reported. This will include a descriptive study of the different solutions envisaged which are based on the following topologies: a)- Monolithic pulse transformer based; b)- Direct switch; c)- Marx generator; d)- Interleaved multi-level converters association; e)- Multi-level resonant converters association.
These topologies will be qualitatively assessed on the context of the ESS project taking items like reliability, maintainability, reparability, efficiency, and safety as comparative criteria.