A beam dump power supply consists of an input stage e.g. active front end with circuit breaker and contractor, a DC-link capacitor bank and 3 bipolar output stages with filters, measurement and redundancy/grounding switches. The output stages have to be bipolar with H-bridge design.

The magnetic fields of the beam dump magnets are perpendicular to each other. By this the beam can be steered in a circular Lissajous curve. The magnet sinusoidal currents have a phase shift of 90°.

Fig. 1 shows the principle schematic. The inverter plus filter and measurement is called power supply (PS). Inverter 1 corresponds to power supply 1 (PS_1) etc.

The input is connected to the 400 V mains. It charges the DC link capacitor with constant power.

The capacitor bank has to provide the energy for bipolar PS that supply the dump magnets with alternating sinusoidal currents. During the rising slope of the magnet current, the DC link will supply energy for the magnet. On the falling slope of the magnet current; the energy will be fed back into the DC link. The capacitance has to be chosen to more than 5 F in order to keep the voltage variation small. The capacitor current and voltage have to be measured.

For the operation of the beam dump supply, 2 PS will be active and will feed the magnet loads. In case of a failure the broken PS will be disconnected from the load and the third PS will be switched onto the magnet and activated. The switches are called redundancy switches. They will contain also a grounding switch that short circuits the output of the supply to ground to allow save work at the magnets.

Nominal output current: +/- 140 A

Nominal output voltage: +/- 130 V

Operation frequency of magnet current 0.3 to 0.4 Hz

Adjustable frequency steps 0.01 Hz

Output ripple max at PWM frequency: 1.0 V pp

Other frequencies < 0.1 V

for higher frequencies see EMC Standards

Power input voltage 400 V 3~ +/- 10 %, 50 Hz

Auxiliary supply voltage: 400 V 3~+neutral and PE +/- 10 %, 50 Hz, with CEE connector

Output ripple frequency > 22 kHz

Insulation voltage of the power part to ground: 2.5 kVrms

Insulation resistance to ground: > 10 M

Ambient temperature: 10 – 50 °C

MTBF >70 000 hrs.