High Voltage modulators ESS developments Carlos A. Martins ESS Accelerator Division, RF electrical power systems

Reduced Scale modulator prototype ( SML topology status on Sept 2015 ) Electrical schematic Part I – Low Voltage power converter: successfully tested in Feb on resistive loads Part II – HV oil tank assembly: - first HV module prototype built from Feb to June 2015 and successfully tested with a 25kV dummy load in July 2015, in combination with Part I Part I Part II

Integrated test of Low Voltage power converter with High Voltage module #1, at LTH (July 2015) Part I – Low voltage power converter Part II – HV module prototype in oil tank Experimental results at full power: Pulsed at 20kV/20A, 3.5ms/14Hz (Note: no output filter present; waveforms are as expected) HV module prototype in assembly workshop at LTH Magenta: HV output pulse; Yellow: LV input voltage; Green: LV input current 3.5ms pulse zoom

3 D Model of the complete HV oil tank assembly ( containing 6 HV modules and output filter stage ) Silica gel breather Tank lid Inspection lid HV output connector Water cooling serpentine -Design and 3D model started in Feb 2015 and completed in June 2015; -Technical specification for “build to print” contracting ready in June 2015; -Invitation To Tender (ITT) for construction launched on 2 nd July 2015; -Offers received on 10 th September 2015; External view Internal view Longitudinal cut view HV modules HV output filter capacitor banks HV rectifier box HVHF transformer Fiberglass insulation frame HV module LV feedthroughs HV sensor

Reduced Scale modulator prototype ( SML topology status on March 2015 ) Part I – Low Voltage driver: → successfully tested in Feb on resistive loads Part II – HV oil tank assembly: → Delivered at LTH test stand on March 4 th → Tests undergoing. Should be completed shortly Part I Part II Electrical schematic

Reduced Scale modulator prototype ( Progress in construction and testing of HV oil tank assembly) 2)- Feb 12 th at manufacturer premises (Lund): - All parts / components delivered; - HV module #1 assembled; 3)- March 2 nd at manufacturer premises (Lund): -HV module #1 to #6 assembled and placed in the frame; 4)- March 23 rd at LTH test stand: - Preliminary testing of the full HV oil tank assembly at low voltage; 1)- Contract signed on Oct 14 th 2015 Yellow: primary voltage of HV module #1 Magenta: primary current of HV module #1 Blue: output voltage pulse (in open loop, no regulation);

High Voltage Anode Power Supplies for Tetrode Amplifiers Baseline (our view): - 40 kVA Anode power supply (2 pair of tetrodes per power supply) 18kV / 2.2 A T1a T1b Keypoints: -Integrated system (short HV cables, short control cables, integrated control and interlock system); -Minimal stray inductance of the HV cables; -Cost of HVPS is similar if standard off-the-shelf modules are used; -Cost of capacitor bank is similar; -Time to repair is reduced considerably (one rack system, entire rack can be easily changed if needed); -Series of 26 units makes some cost reduction due to series effect (medium quantities); -Many companies in HV can design, build and test this kind of system; Challenges: -Electrical network power quality issues, including harmonic distortion and flicker mitigation

High Voltage Anode Power Supplies for Tetrode Amplifiers Possible implementation: - 40 kVA Anode power supply (2 tetrodes per power supply) 18kV / 2.2 A T1a T1b HV capacitor charger HV capacitor bank HV series switch 150 mm x 150 mm x 250 mm

High Voltage Anode Power Supplies for Tetrode Amplifiers Possible mechanical layout: - 40 kVA Anode power supply (2 tetrodes per power supply) Estimated series (26 units) cost: ~ 130 kEURO / each