Many nuclear physicists working with big tandem Van de Graaffs would like to raise the energy of their accelerators by buying new acceleration tubes from. High Voltage Engineering Corp. In tests with its own MP‐0 (Emperor) tandem Van de Graaff, High Voltage reported that voltages as high as 14.4 MV were achieved, which the company says is the highest dc voltage ever applied to an acceleration tube. In the past, tandems only ran at 10–11 MV on terminal; beyond this value the tubes would fail. With the new tubes, a conventional tandem would be able to run at 28–30 MeV.