Researchers in the Neutron Sciences Directorate at Oak Ridge National Laboratory (ORNL) received delivery of a pulsed high-voltage power supply, referred to as the “JEMA Modulator,” on February 28 as part of a cooperative research and development agreement between ORNL and European Spallation Source (ESS)-Bilbao. This power supply was developed and fabricated by JEMA Energy in Lasarte-Oria, Spain using high-power insulated gate bipolar transistors to perform the power conversion and compression.

The JEMA Modulator is being installed and will be tested in building 8320 at the Spallation Neutron Source (SNS) site. The modulator will undergo a 30-day continuous full average power test of the system at up to 85 kV and 160 A, after which the SNS researchers will retain the modulator for up to three years for on-going research and development testing.

The modulator is used to deliver pulses of electricity to klystron tubes, which convert the electricity to microwave energy. The microwave energy is then used to accelerate the H-ions through the SNS linear accelerator, or Linac. The JEMA modulator offers several advantages over competing modulators, such as the SNS high voltage converter modulators (HVCM). Perhaps the most significant one is that the unit has one out of twelve output modules that is redundant, allowing the modulator to continue operating uninterrupted should one module fail. This feature should result in significant availability improvements over the existing SNS HVCMs.

The JEMA Modulator was designed to meet SNS requirements for increasing the Linac output energy by adding additional cryomodules and radio frequency stations to the end of the existing Linac. This program, if successful, will result in a candidate modulator design for the Second Target Station upgrade of the SNS facility and a new modulator topology that could find uses at other accelerator facilities worldwide.