LINAC LOW ENERGY MODULATORSSTATUS UPDATE

FERMILAB DESIGNHowie Pfeffer/Jim Biggs

12/19/12

FERMILAB SPECS

SOME OF THE TOUGH SPECS:Beam Top Tilt (Adj.): +/- 5 kVBeam Voltage Step SR: 15 kV/usecFlattop/Beam Regulation: +/- 25 VRepeatability: +/- 10 VMaximum spark Energy: < 5 Joules

SOME SPECSPulse rep rate: 15 HzMaximum Output: 35 kVLoad ~100 ohmRise time (Adjustable): 150 usecFall time (Adjustable): 150 usecFlat top time (Adjustable): 160 usecBeam Length/Time (Adj.): 110 usecMaximum step size: 1.5 Kv

Essentially a 35kV, 350 amp, OPAMPCapable of 15 kV/usec slew rate

BLOCK DIAGRAM OF PROPOSAL

MARX PS BLOCK DIAGRAM

BASIC TEST CIRCUIT

SnubberCurrent GenerationCircuit

BASIC TEST CIRCUIT

CURRENT WITH STEP

Current

IGBT 40U.5.6UHI DIRECTCurrent

Collector Volt

Emitter Volt

SNUBBER CAPACITOR MOUNTING

SHORT CIRCUIT DURING TURN ON TEST CIRCUIT

900 VOLT – GATE VOLTAGE

Collector Volt

Gate Volt

Gate Control

CT1 Current

900 VOLT, 20 USEC

Collector Volt

Gate Volt

CT1 Current

CT2 Current

SHORT DURING PULSE TEST CIRCUIT

CONCLUSIONS IGBT Switching action has been

confirmed with acceptable transient voltages.

IGBT short circuit current limiting and safe turn-off have been confirmed for turning on into a short and “spark-type” short circuits.

Design for a 10 stage pulser is complete.

FUTURE PLANS Starting to specify and order parts for

10-stage Expect to have parts ordered by end of

January Parts should be here in 3 months Begin mechanical design and layout

beginning of February.