A Very Simple B2Spice Simulation of the Veradyne 8 Stage Marx


By Vaughn P. McDowell



A Marx generator is a high voltage multiplier impulse generator; its operation consists of first charging high voltage capacitors in parallel followed by discharging them in series.1 The schematic shown below is a very simplified representation of an 8 stage Veradyne Marx 2,3. C1 - C8 are 2.7nf ceramic capacitors rated at 40KV; each is charged in parallel by charging resistors connected in series composing two charging rails. A HV charging power supply is connected to node 2 (via an isolation resistor not shown); the high voltage rail consists of R4, 1, 7,6,10,12, and 14 (50K each). The capacitor’s ground charging rail is via R2, 3,5,8,9,11,13,15 respectively.

The closing switches are typically spark gap switches which in this case are represented by the SW_tSigmoid closing switches initially open. For this simulation the capacitors are initially charged to 40kv followed by connecting them in series in sequence C1,2 ,3 ..etc. When all switches are closed the Marx output is 8 X 40KV = 320KV at node 23. The last closing switch is known a the peaking spark gap which sharpens the output at node 24. C9 and R16 represents the Marx load.

The Marx output waveform is shown below at nodes 6, 10,12,23, and 24; one can see the Marx erection process by observing 6 - 23 and peaking at 24.

The switch parameters include t DELAY {TD} and t RISE{TR}; the values I chose was for illustrative purposes only (from left to right TD\TR in nsec :0\15, 1\12,2\10,310,3.5\10,4\10,4.5\9,5\8, and 6\10).

References:

  1. “High-Power Electronics” W. J. Sarjeant and R.E. Dollinger , TAB Books Inc. 1989 pg. 87

  2. “10-Joule 200kv Mini Marx” David Platts Los Alamos Lab MS K302

  3. “Minimarx High Voltage Trigger Generator P/N 50082” Veradyne Corp. Energy Sys Div.; no longer available to my knowledge

Netlist:

Veradyne1B.cpr

***** subcircuit definitions

.subckt X9_X8_X4_X2_SW_tSigmoid_0 n2 n3
v1 4 0 dc 0 pulse(0 1 6.000000000000e-009 1.000000000000e-008 1e-6 1 2)
b1 n2 n3 i=v(n2,n3)/v(5,0)
r1 4 0 10meg
b2 5 0 v= 1.000000000000e+007/(1 + exp(28*(v(4,0))))
r3 5 0 1k
.ends sw_tsigmoid

.subckt X8_X4_X2_SW_tSigmoid_0 n2 n3
v1 4 0 dc 0 pulse(0 1 5.000000000000e-009 8.000000000000e-009 1e-6 1 2)
b1 n2 n3 i=v(n2,n3)/v(5,0)
r1 4 0 10meg
b2 5 0 v= 1.000000000000e+007/(1 + exp(28*(v(4,0))))
r3 5 0 1k
.ends sw_tsigmoid

.subckt X7_X4_X2_SW_tSigmoid_0 n2 n3
v1 4 0 dc 0 pulse(0 1 4.500000000000e-009 9.000000000000e-009 1e-6 1 2)
b1 n2 n3 i=v(n2,n3)/v(5,0)
r1 4 0 10meg
b2 5 0 v= 1.000000000000e+007/(1 + exp(28*(v(4,0))))
r3 5 0 1k
.ends sw_tsigmoid

.subckt X6_X4_X2_SW_tSigmoid_0 n2 n3
v1 4 0 dc 0 pulse(0 1 4.000000000000e-009 1.000000000000e-008 1e-6 1 2)
b1 n2 n3 i=v(n2,n3)/v(5,0)
r1 4 0 10meg
b2 5 0 v= 1.000000000000e+007/(1 + exp(28*(v(4,0))))
r3 5 0 1k
.ends sw_tsigmoid

.subckt X5_X4_X2_SW_tSigmoid_0 n2 n3
v1 4 0 dc 0 pulse(0 1 3.500000000000e-009 1.000000000000e-008 1e-6 1 2)
b1 n2 n3 i=v(n2,n3)/v(5,0)
r1 4 0 10meg
b2 5 0 v= 1.000000000000e+007/(1 + exp(28*(v(4,0))))
r3 5 0 1k
.ends sw_tsigmoid

.subckt X4_X2_SW_tSigmoid_0 n2 n3
v1 4 0 dc 0 pulse(0 1 3.000000000000e-009 1.000000000000e-008 1e-6 1 2)
b1 n2 n3 i=v(n2,n3)/v(5,0)
r1 4 0 10meg
b2 5 0 v= 1.000000000000e+007/(1 + exp(28*(v(4,0))))
r3 5 0 1k
.ends sw_tsigmoid

.subckt X3_X2_SW_tSigmoid_0 n2 n3
v1 4 0 dc 0 pulse(0 1 2.000000000000e-009 1.000000000000e-008 1e-6 1 2)
b1 n2 n3 i=v(n2,n3)/v(5,0)
r1 4 0 10meg
b2 5 0 v= 1.000000000000e+007/(1 + exp(28*(v(4,0))))
r3 5 0 1k
.ends sw_tsigmoid

.subckt X2_SW_tSigmoid_0 n2 n3

v1 4 0 dc 0 pulse(0 1 1.000000000000e-009 1.200000000000e-008 1e-6 1 2)
b1 n2 n3 i=v(n2,n3)/v(5,0)
r1 4 0 10meg
b2 5 0 v= 1.000000000000e+007/(1 + exp(28*(v(4,0))))
r3 5 0 1k
.ends sw_tsigmoid

.subckt SW_tSigmoid n2 n3
v1 4 0 dc 0 pulse(0 1 0.000000000000e+000 1.500000000000e-008 1e-6 1 2)
b1 n2 n3 i=v(n2,n3)/v(5,0)
r1 4 0 10meg
b2 5 0 v= 1.000000000000e+007/(1 + exp(28*(v(4,0))))
r3 5 0 1k
.ends sw_tsigmoid


***** main circuit
C1 2 6 2.7nf ic = 4.000000000000e+004
C2 3 7 2.7nf ic = 4.000000000000e+004
R2 0 6 60K
R3 6 7 60K
R1 3 5 60K
R4 2 3 60K
XX1 0 2 SW_tSigmoid
R7 5 9 60K
XX2 6 3 X2_SW_tSigmoid_0
R5 7 10 60K
C3 5 10 2.7nf ic = 4.000000000000e+004
R9 14 12 60K
XX3 7 5 X3_X2_SW_tSigmoid_0
R6 9 13 60K
R8 10 14 60K
C4 9 14 2.7nf ic = 4.000000000000e+004
XX4 10 9 X4_X2_SW_tSigmoid_0
C5 13 12 2.7nf ic = 4.000000000000e+004
XX5 14 13 X5_X4_X2_SW_tSigmoid_0
R10 13 16 60K
R11 12 18 60K
C6 16 18 2.7nf ic = 4.000000000000e+004
XX6 12 16 X6_X4_X2_SW_tSigmoid_0
R12 16 20 60K
R13 18 22 60K
C7 20 22 2.7nf ic = 4.000000000000e+004
R16 24 0 14K
XX7 18 20 X7_X4_X2_SW_tSigmoid_0
R14 20 19 60K
R15 22 23 60K
C8 19 23 2.7nf ic = 4.000000000000e+004
XX8 22 19 X8_X4_X2_SW_tSigmoid_0
XX9 23 24 X9_X8_X4_X2_SW_tSigmoid_0
C9 24 0 2pf ic = 0


.TRAN 1E-10 2E-8 0 1E-10 uic

.OPTIONS temp = 27
.end