The pulsed high voltage power converters, also known as modulators, energize the klystrons for the ESS LI- NAC’s RFQ and DTL tanks. A total amount of 3 modu- lators is required for 6 klystrons, i.e.: each modulator powers two klystrons in parallel. These modulators are based on an advanced topology developed by ESS ERIC RF team with the help of Lund University, known as Stacked Multi-Level (SML).

This topology is able to provide high quality pulses, outs- tanding efficiency and low flicker, while exhibiting high power density in a relatively reduced footprint.

ESS Bilbao took over the responsibility to procure the first 3 modulators, based on a “built-to-print” strategy, where ESS ERIC provided a complete design dossier. The contract was awarded to Jema Energy, S.A., a Basque company specialized in the design and manu- facturing of turnkey energy conversion systems. Jema Energy, a lifelong partner of ESS Bilbao, undertook the industrialization of the design and the manufacturing and factory tests of the three modulators.

The in-kind contribution was executed on the basis of a joint collaboration between the parties (ESS ERIC, ESS Bilbao and the industrial partner), with shared responsabilities and due regard to the prime interests of the ESS project overall.

The main specifications of the klystron modulators are:
  • Type SML pulsed klystron modulator.
  • Pulse type square, with negative polarity.
  • Nominal pulse voltage amplitude: -115 kV.
  • Nominal pulse current amplitude: 100 A.
  • Nominal pulse power amplitude:  11.5 MW.
  • Nominal pulse repetition rate: 14 Hz.
  • Nominal pulse width (at 50% of magnitude): 3.5 ms.
  • Minimum efficiency at nominal conditions: 91%.

The modulators manufacturing is being carried out by JEMA Energy.


HV module simulation