Rapid-Cycling Synchrotron extraction-kicker magent-drive system Page: 1 of 4
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THE RAPID-CYCLING SYNCHROTRON EXTRACTION-KICER MAGNET-DRIVE SYSTEM*
THI REPORT ARE ILLEGIBLE. Dale E. Suddeth and Gerald J. Volk Cc
Shte best Argonne National Laboratory
avahasben rproducto er om Argonne, Illinois 60439
posse permit the broader D
available copy 83 0044
possible availability. Abstract r Series Charge ControlThe Rapid Cycling Synchrotron- (RCS) accelerator
of the Intense Pulsed Neutron Source-I (IPNS-I) at
Argonne National Laboratory utilizes a fast kicker mag-
net to provide single-turn extraction for a 500-MeV
proton beam at a 30 Hz rate. The single-turn, 0.89-m-
long ferrite magnet is broken up into two identical
cells with four individual windings. Each winding re-
quires a 4863-A magnetizing current into a 7.0-4 load
with a rise time of less than 100 ns and a flattop of
about 140 ns. Pulse forming network (PFN) charging
and switching techniques along with the components
used will be described.
Introduction
The power supply system was divided into two
identical sections which individually pulse each cell
of the fast kicker magnet's two-cell design.: Although
required to operate at 30 Hz, the system was designed
to accommodate the future upgrade of the RCS from 30 Hz
to a 45 Hz machine. System reliability and ease of
maintenance were of prime importance.
Specifications
Each of the four magnet windings are to be driven
from individual PFN's with a characteristic impedance
of 7.0 0 providing a 4863 A magnetizing current adjust-
able to i 10% with an overall system rise time of
< 100 ns and a flattop of at least 140 ns. Allowing
10 ns jitter with a magnet cell rise time (L/R) of
78 ns requires the basic nower supply system to have a
rise time of <V100 nsi-88 nsa - 47.3 ns.
Although the present pulse repetition rate (PRR)
requirement is 30 Hz, the system will be designed to
accommodate the future RCS upgrade to 45 Hz. The sys-
tem must also be capable of operating at PRR's of 3 Hz,
5 Hz, 10 Hz, and 15 Hz and maintain a regulation of
less than 1%.
Pulse Formine Network
Supplying a 4863 A pulse from a 7.0 2 PEN into a
7.0 2 magnet termination requires charging the PEN to a
voltage of 4863 A x 7 l x 2 w 68 kV. Obtaining the
correct pulse flattop of 140 ns witn a rise time of
100 ns requires the total propagation time of the PFN
to be 140 ns 100 s 120 ns.
in view of these requirements, each PFN was con-
structed by paralleling two 14 2, 100 kV, Belden
type YR-10914 pulse rated coaxial cables. With an
inductance of 98.4 nH/M and capacitance of 455.9 pF/M,
the propagation time of t-e cable isV LC w 6.70 ns/M.
Each PFN cable length, therefore, is 120 ns - 17.9 M.
6.70 ns/M
High voltage insulation and cooling, via water
cooled heat exchangers, was acquired by constructing
the system in oil-filled tanks. Segregating each power
supply section into separate charge control and thyra-
tron discharge tanks allows both ends of the PFN cables
to be terminated in oil.
Work supported by the U. S. Department of Energy.Insuring equal voltages on all FN cables needed
per magnet cell requires charging from a common series
voltage regulator. Allowing for the +101 adjustment
requested, the system was designed to operate with a
maximum PFN voltage of 75 kV at a PRR of 45 Hz. For
45 Hz operation the allowable charge time selected is
18 ms and for 30 Hz operation 28 ms. With PFN parame-
ters and charge times fixed, the series regulator and
operating power supply requirements can be determined.
The total capacitance of PFN cables to be charged
is 4 x 18 m x 455.9 pF/m - 32.82 nF. Charging current
for 45 Hz operation:
S75 x 103
I - C dvydt - 32.62 x 10' x 0.018 - 136.77 m.
Power dissipation of the series regulator:
(75 x-103) x (136.77 x 10-) 0.018 -
PAV AV AV 2 x 0.022
4.20 kW.
The cascade-type circuit of Fig. 1 is used as the
series voltage regulator and is controlled with a single
bias and switching module. Four EIMAC type 8960 pulse
modulator tetrodes, each rated for 1.2 kW at 50 kVwere
selected as series control elements.
The bias and switching module of Fig. 2 receives
an on-off infrared gate pulse generated by the logic
level voltage control feedback loop. Pulsing both con-
trol and screen grids of the master tetrode provides
sufficient drive to charge the PFN's to a predetermined
voltage within the allotted time. Both grid gate sig-
nals are generated simultaneously with the circuit's
main switching transistor, a 2116214. Fine tuning of
the charge time is acquired by adjusting the pulse lev-
el on the control grid with a motor driven 10-turn
potentiometer.
Isolation between the two PFN sets and the series
regulator is provided with wire-wound 100 W resistors.
Due to the inherent inductance of wire-wound resistors,
additional isolation is provided during the rapid dis-
charge cycle of the FFN's. American Components'high
voltage resistors type ROX-4 were used for the tetrode
dividers, and type ROX-3 for the voltage feedback divid-
er and thyratron gap dividers in the thyratron discharge
circuit.
Thvratron Discharge Circuit
English Electric Valve type CX-1192 thyratrons are
used as PFN discharge switches. They were selected for
their low jitter, voltage, and current handling speci-
fications. Mounted in coaxial housings to minimize
stray inductance, each thyratron has plug-in printed
circuit cards for bias and trigger control modules.
Figure 3 shows the schematic diagram of the discharge
circuit and the connection to the magnet and load as-
semblies. Preserving the system impedance, magnet and
load transmission lines also use the Belden YR-10914
coaxial cable.)NF-810314--186
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Suddeth, D. E. & Volk, G. J. Rapid-Cycling Synchrotron extraction-kicker magent-drive system, article, January 1, 1981; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc1211376/m1/1/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.