te MARX Type Circuit for the E Target Voltage Modulator

Solid-State MARX Type Circuit for the ISOLDE Target Voltage Modulator

22 Set 2009EPPC 09 CERN

21-25 September

L.M. Redondo*, J. Fernando Silva#, H. Canacsinh*, N. Ferrão*, C. Mendes*, R. Soares†, J. Schipper

Work supported by FCT project

* Nuclear Physics Center - Lisbon University (CFNUL), Lisbon, Portugal# Center for Innovation in Electrical and Energy Engineering

† ABT Group, TE Department, CERN, Switzerland

State MARX Type Circuit for the ISOLDE Target Voltage Modulator

EPPC 09 CERN September 2009 1/14

, H. Canacsinh*, N. Ferrão*, C. Mendes*, , J. Schipper† and A. Fowler†

Work supported by FCT project CERN-FP-83497-2008

Lisbon University (CFNUL), Lisbon, Portugal# Center for Innovation in Electrical and Energy Engineering – TU Lisbon, Lisbon, Portugal

† ABT Group, TE Department, CERN, Switzerland

Summary

• ISOLDE Target Voltage Modulator (the actual system, the issues, the motivation);

• System requirements and new concept

• Proposed solid-state modulator;


21-25 September

• Proposed solid-state modulator;

• Prototype layout and experimental results

• Conclusions and future work

Summary

ISOLDE Target Voltage Modulator (the actual system, the issues, the motivation);

System requirements and new concept;

state modulator;


state modulator;

Prototype layout and experimental results

Conclusions and future work

ISOLDE Target Voltage Modulator

The On-Line Isotope Mass Separatorfacility uses the 1.4 GeV proton beam (up to 2 µA ) from the PS-booster at CERN to bombard a target and produce a wide range of isotopes.

To provide the needed acceleration, the target and ion source must be held at a


21-25 September

The impacting proton beam intensivelythe accelerating voltage because it representspower supply.

target and ion source must be held at a precise voltage (60 kV±1V), with respect to a grounded extraction electrode, if there is to be high mass resolution in the downstream separator.



ionises the air. This ionisation perturbsrepresents a significant additional load on the

During the critical period when protons strike the target the accelerating voltage is modulated to zero. This is acceptable provided that the stable accelerating voltage of 60 kV +/- 1 V is interrupted for less than 10 ms, so still allowing the detection of very short life-time radio isotopes.


[3] D.C. Fiander, A. Fowler, in 20th Power


21-25 September

At present a custom-built positive 60 kV d.c. power supply (PS), Iconnected, via a pulse transformer and a hardcircuit such that prior to beam impact the target is fully circuit in 35µs, which then restores the voltagefurther 200µs. Finally, returns to its nominal value ± 1 V within 5 to 6 ms.

[3] D.C. Fiander, A. Fowler, in 20 Power Modulator Symposium, 1992, pp. 173-176.

1 V is interrupted for less than 10 , so still allowing the detection of very short

ISOLDE Target Voltage Modulator60 kV


built positive 60 kV d.c. power supply (PS), Imax<40 mA, is connected, via a pulse transformer and a hard-tube switch (tetrode), to a resonant

such that prior to beam impact the target is fully discharged by the resonant restores the voltage close to its nominal value within a

1 V within 5 to 6 ms.


The high precision, high stability power supply PS2, is connected to C2, almost two orders of magnitude greather than C4 (load), for minimising the voltage excursion.

The current limitation on the 60 kV PS limits the circuit performance.


21-25 September

C4 voltage

C2 voltage


The high precision, high stability power supply PS2, is connected to C2, almost two orders of magnitude greather than C4 (load), for minimising the voltage excursion.

The current limitation on the 60 kV PS limits the circuit performance.


To ensure future physic requests, such as the power increase of the proton beam, for both negative and positive short life-time radio isotopes ion beams, necessary improvements must be made on the existent modulator circuit.

System requirements and new concept

Udc

S1

Rdc

Cdc

The 60 kV PS, the device that controls theshielding against any voltage variations.


21-25 September

The new circuit concept uses the actual 60 kVbased on the solid-state Marx modulator concept

• one in series, S1, between the PS and the load,prior to proton beam impact;

• another one in parallel, S2, with the load thatit to full voltage afterwards (position 2), just beforeload voltage stability.

System requirements and new concept

Ua

S2

1

2

dc C0 R0

Ra

the accuracy of the target voltage, must be


kV PS and two auxiliary high voltage switches,concept:

load, R0/C0, which disconnects the PS from load

that discharges it to zero (position 1), rechargingbefore the 60 kV PS takes control again of the

Positive Solid-State Marx generator operation

Tp1

Tc1

C1 C2

Dc1

Tp2

Tc2

Dc2

Cn-1

Tp(n-1)

Tc(n-1)

Dc(n-1)

Tpn

Tcn

Cn

Tc0

Vdc

rdc

Load

i0

v 0

[2] L.M. Redondo, J. Fernando Silva, P. Tavares and E. Margato, in IEEE 36th PESC Conf., 2005, pp.1170-1174

Topology


21-25 September

tp

vgs(Tpi)

vgs(Tci)

Vi

Vi

T

tc

v0

+nVdc0

0

0

dp=tp/T

dc=tc/T

State Marx generator operation

Tc1

C1 C2

Dc1

Tc2

Dc2

Cn-1

Tc(n-1)

Dc(n-1)

Tcn

Cn

Tc0

Vdc

rdc

Load

i0

v 0

L.M. Redondo, J. Fernando Silva, P. Tavares and E. 1174.

Charging mode


Tp1

C1 C2

Tp2

Cn-1

Tp(n-1) Tpn

Cn Load

i0

v 0

t

t

t

Pulse mode

Proposed Solid-State Modulator

Marx 1

Cn

Dpn

Tcn

Udc

Rdc

vc v0

Cdc

Dp1

Tc1

C1C2

Dc1Dc(n-1)

vm1


21-25 September

R

Two n stages solid-state Marx generators,(Marx 1) and parallel (Marx 2) switch.

State Modulator

C

Udc2

Tpn

Cn

Tcn Tc1

C1C2

Dc1Dc(n-1)

Tp1

Rdc2

Marx 2


TargetR0

C0

generators, operating, respectively, as a series

Marx 1

Tcn

Udc

Rdc

Target

vc v0

Cdc

R0

C0

Udc2

Tc1 Tpn

Cn C1C2

Tp1

Rdc2

Marx 2

vm1

Proposed Solid-State ModulatorMode 1


21-25 September

Mode 1, time t0:• Tci in Marx 1 are on, the Ci capacitors in Marx 1 are in parallel;• Tci and Tpi in Marx 2 are off, Ci capacitors are in series, through the Tpi anti-parallel diodes, distributing the voltage across Tci. • Capacitor Cdc voltage, vc, is applied to the load, v0.

Tt1

t3

t0vTci M1

vTci M2

vTpi M2

0

0

0

vc

t

t

t

(a)

(b)

(c)

State Modulator


t2

0

0

0v0

vm 1

t

t

t

(d)

(e)

(f)

Marx 1

Cn

Dpn

Udc

Rdc

Target

vc v0

Cdc

R0

C0

Udc2

Dp1

C1C2

Cn

Tcn Tc1

C1C2

Dc1Dc(n-1) Rdc2

Marx 2

vm1



21-25 September

Mode 2, time t2:• Tci in Marx 1 are off, vc appears between theterminals, and is sustained by the Ci capacitorsin series through the diodes Dpi, distributing thevoltage across the Tci.• Tpi and Tci in Marx 2 are, respectively, off andon;• The load is discharge to zero.

dc2

State Modulator

Tt1

t3

t0vTci M1

vTci M2

vTpi M2

0

0

0

vc

t

t

t

(a)

(b)

(c)


thecapacitors

the

and

t2

0

0

0v0

vm 1

t

t

t

(d)

(e)

(f)

Marx 1

Tcn

Udc

Rdc

Target

vc v0

Cdc

R

C0

Udc2

Tc1 Tpn

Cn C1C2

Tp1

Rdc2

Marx 2

vm1



21-25 September

R0

Mode 3, time t3:• Tci in Marx 1 are off;• Tpi and Tci in Marx 2 are, respectively, on andoff, and the Marx 2 applies a voltage to theload, charging it;• The load is charged to about ~nUdc2.

dc2

State Modulator

Tt1

t3

t0vTci M1

vTci M2

vTpi M2

0

0

0

vc

t

t

t

(a)

(b)

(c)


andthe

t2

0

0

0v0

vm 1

t

t

t

(d)

(e)

(f)

Prototype layoutFront


21-25 September

Marx 1

Prototype layout

Back

10 kV, prototype10 stages 1 kV Marx1200 V IGBTs, diodes and capacitors


Marx 2

Experimental results10 kV, prototype

Udc=10 kV,Udc2=1 kV,R0=14 MΩCi=1 µF, with 1.8 M

~ 20 Hz, t

250 µs reset time, 250 ns rise and fall times

Load voltage

Load voltage

2000 V/div 10 ms/div


21-25 September

250 ns rise and fall times40 kV/µs slew rate. 3 ms recovery time

Load voltage

2000 V/div 100 µs/div

Experimental results10 kV, prototype

kV, Rdc=2.7 kΩ, Cdc=200 nFkV, Rdc2=1 kΩ

=14 MΩ, C0=2 nFµF, with 1.8 MΩ in parallel

~ 20 Hz, t0=50 ms, t2=254 µs and t3=10 µs

s reset time, 250 ns rise and fall times C voltage


250 ns rise and fall timesµs slew rate.

3 ms recovery time

2000 V/div

Cdc voltage

10 ms/div

• A new solid-state Marx type topology was proposed for the ISOLDE Target Voltage Modulator;

• Solid-state Marx generators were used as serial and parallel switches;

• The new topology minimizes the effects on the PS from the load voltage excursions

• Preliminary results, from a 10 kV prototype, were presented with two, ten stages 1 kV, Marx generators, with 1200 semiconductors;



21-25 September

stages 1 kV, Marx generators, with 1200 semiconductors;

• Voltage ripple is, mainly, due to the parameters Rsystem as well as the value of the resistors connected in parallel with the Ccapacitors in the two Marx generators;

• It is mandatory to further increase the voltage amplitude to near the 60 kV regime and test the circuit in the off-line target.

state Marx type topology was proposed for the ISOLDE Target

state Marx generators were used as serial and parallel switches;

The new topology minimizes the effects on the PS from the load voltage

Preliminary results, from a 10 kV prototype, were presented with two, ten stages 1 kV, Marx generators, with 1200 semiconductors;



stages 1 kV, Marx generators, with 1200 semiconductors;

Voltage ripple is, mainly, due to the parameters R0/C0 and Rdc/Cdc of the system as well as the value of the resistors connected in parallel with the Ci

It is mandatory to further increase the voltage amplitude to near the 60 kV line target.

te MARX Type Circuit for the E Target Voltage Modulator

Documents

Transcript of te MARX Type Circuit for the E Target Voltage Modulator