HIGH PULSE AND AVERAGE POWER LOW-INDUCTION LOAD
B.I.Grishanov, F.V. Podgorny, BINP, Novosibirsk, Russia
Abstract
A high pulse and average power low-induction
load with a built-in divider is described in this report.
The load has a nominal resistance of 25 Ohm and isdesigned to operate with a repetition rate of up to 50
Hz at a pulse duration (FWHM) of 100 ns, a rise/falltime of 50 ns and pulse amplitude of up to 50 kV. In
this mode the dissipated energy is equal to about 10J per pulse and average power is up to 500 W. At
such a short pulse mode there is practically no heatremoving from the load resistant layer during one
pulse. Therefore the absorbing resistor should have alarge heat capacity of the conducting layer. To fit
this condition the resistor is realized as a package ofresistive rings connected in series, a number of
insulating spacers and two terminal connectors. This
construction is placed in a cylindrical insulating tube
connected to a water-cooling system. The design ofthe load provides for a radial pumping of a coolant
between conducting rings. The resistant element has
external diameter of 50 mm and an axial length of
250 mm. The resistor can be used as an absorbing
load and as a circuit element in high-voltage
engineering.

1 INTRODUCTION
The structure of the charged particles acceleratingcomplexes includes various assemblies, including an
injection-extraction system. Usually such a system
consists from kickers itself, deflecting charged
particles beams, high-voltage pulsers for kickers
feeding, pulses transition lines from pulsers to kickers,
loads and other elements. The peculiar properties ofsuch systems operating modes are high pulse powerand energy capacity. Therefore loads (and others
resistive elements of the circuits) should be suitable for
operate in such modes. Thus it is necessary to notefeatures of the resistor heat mode: during a pulse there
is no essential heat eliminate from volume, in which
the energy is dissipated, as a rule.
The accelerating complex VEPP-5 of the colliding
electron-positron beams is under constriction this time in
the Budker Institute for Nuclear Physics of Siberian
Branch of Russian Academy of Science.
This project includes an injection complex consists of aforinjector–linac and a damping ring.
The authors have designed generators for the storage
ring kickers with the following characteristics:

Traveling wave voltage ................................ up to 40 kV
Load resistance.................................................... 25 Ohm
Pulse duration (FWHM) ....................................... 100 ns
Rise/fall time........................................................... 50 ns
Repetition rate................................................up to 50 Hz
Pulse power................................................ about 70 MW
Pulse energy capacity .......................................about 10 J
Average power .............................................about 500 W

2 POWERFUL PULSE RESISTOR TYPES
2.1 Industrial resistors
The industry produces some types of resistors,
appropriated for operation at the specified duration oftransients.
Manufactured in Russia high-frequency powerfulresistors, such as MOU, are executed by applicationof a thin conducting film on a ceramic tube.
A thickness and a heat capacity of this film are tiny.
Resistors of such kind allow to dissipate a generous
power in continues mode. However in the pulse
modes film overheats and distortion is arises during apulse. It limits an admissible pulse work parameters
at rather low level.
It is necessary to enhance a thermal capacity andresistance element volume correspondingly forincreasing the pulse characteristics of the resistors.
Russian industry produces wire-bound resistors S540 also. This resistor is a bifilar winding type.
However these resistors have appreciable inductance.
A time constant became inadmissible big – about of
100 ns and more – at low values of a resistance. In [1]are described experimental samples of such typeresistors, but their limitations are similar mentionedabove.
We know firms, which delivers high power solid(volumetric) non-inductive resistors. CESIWID Inc.,and their "bulk ceramic" construction permits highlevel of energy to be uniformly absorbed throughout
the resistor body – thereby avoiding failure in aperipheral film or wire. Productions of other firm
HVR are widely used in pulse devices. Accelerating
conferences proceedings contain information on such
resistors applications in powerful pulse facility. Our
team assumes to use these resistors in novel
developments.

2.2 Electrolytic resistors
Electrolytic (fluid) resistors have a huge energy
capacity. These resistors base on aqueous solution ofsalts or acids. Advantages of such resistors are: an ability

of making of any form resistors, huge energy dissipation
due to a high specific heat capacity and great volume ofelectrolyte, restoration of the electrolyte electric strength
after casual breakdowns, operatively adjustable resistanceby means of the electrolyte replacement with otherconductivity, a significant life time of the resistor.
There are some disadvantages of such resistors: anecessity of electrolyte conditioning – clearing of asolution from reaction products, a danger of installation
pollution at emergency seal failure and electrolyte runout,a high temperature factor of the conductivity, whichreaches 1-2 % per degree. The last one demands a usingof a conductivity stabilization system. It raises a total load
cost rather significant. The liquid resistor "know-how"and using are described in [2].

Figure 1: General view of the bifilar winding resistors

3 STRIP-LOAD

2.3 "Zigzag" wire-wound resistors

3.1 Construction

There is another type of a wire resistor – with so-called"zigzag" winding. The essence of this design, on which
the copyright certificate [3] is received, consists of thefollowing. An isolating cylindrical rod is threaded. Thenthe rod is cut along. These cuts divide the thread to somelongitudinal strips with the cross slots, formed by thisthread. Nichrome wire is placed in each slot, and fixed onswivels. It is possible to change both nominal resistanceof the resistor, and its heat capacity by choosing various
rod diameters, the thread step, the amount of stripes andthe wire thickness. Wires are welded to metal ends of theresistor. This construction type looks like the bifilar
winding resistor. However a number of limits inherent
last one are eliminated here. In figure 1 the general viewof such resistor is shown. Such kind resistors of 50-Ohm
resistance are widely used at voltage up to 50 kV, pulse
duration of tens nanosecond and rise/fall time of several
nanosecond on the BINP complexes. The most powerfulsuch type load had parameters: resistance – 50 Ohm,pulse amplitude – up to 150 kV at resistive element
winding length of the 150 mm, pulse duration – 60 ns,rise/fall time – 3 ns and repetition rate up to 25 Hz. That
corresponds to average power more than 600 W. The
resistor is directly immersed and cooled by flowing water[4]. The disadvantage of such design is a big effort.

The load based on the resistive element having a
strip-line cylindrical bifilar design [5] is described
below.
The resistive element is executed from metal rings.
Each ring is connected with the previous and thefollowing in two diametrically opposite points. As
result two parallel sections of the resistor are formed.
In figure 2 the resistance element is shown stretchedin an axial direction for presentation. It is possible toconnect the rings in more points.

Figure 2: Axially stretched resistance element
The rings are isolated from each other by fiberglass plastic separators. Narrow stripes of separators
isolate the neighbor rings. Cutouts of all separatorsform channels for the cooling liquid in an axial
direction. Connections of all rings are carried out
with the soldering in a single technological cycle. The
soldering was made through linings from the stainlesssteel, preliminary copper-plated by a galvanic way.
There are thick electrodes at end faces of the resistor.
An isolating tube provides an assembly centering andformation of a cooling liquid stream. The resistanceelement is placed in the glass tube, working on a fullvoltage. The general view of load in glass is shown infigure 3.

of 50 Hz. The maximal amplitude was limited bygenerator ability on the moment of tests.
The low voltage test consists of reflection measuring.
At the pulse rise time of 50 ns the reflections amplitude
did not exceed 15%. It is acceptable for damping ringkicker system.

5 ACKNOWLEDGEMENTS

Figure 3: General view of strip load(without metal housing)

3.2 Frequency characteristic
The load of such design could consider as theresistor with superfluous inductance. The time
constant τ = L/R is determined by the relation of alinear inductance between the neighbor rings to thering linear resistance and does not depend on itswidth. The inductance is defined by geometry only,namely, distance between rings and their width. The
ring linear resistance depends on specific resistanceof a material, thickness and width of the ring. For
improvement of resistor frequency properties it isnecessary both to choose a material with the largest
specific resistance and to reduce thickness of therings and gaps between them. Estimations show, thatcapacitive constituent of an impedance it is possible
to neglect.

3.3 Electric strength
The load has a coaxial design. A feature of thisdesign consists of following moments. A round shapeof the resistor permits to eliminate a fieldenhancement on sharp edges. The resistive element isplaced into the glass tube and immersed directly inwater. All assembly is installed in the conducting
housing, which serves a back conductor. A main
insulating medium between the resistor and thehousing is SF6 at superfluous pressure up to 5 atm(kg/sm 2 ). At these conditions the isolation between
the resistive element and the housing consists of threelayers: water, glass and gas. Considering thedielectric properties of these layers the cross gradientin water near the rings becomes rather small.
Therefore the full voltage is applied to a gas gap. It
provides sufficient electric strength of allconstruction.

4 TESTSThe following tests of the load were carried out:
low-voltage tests of a load matching in a requiredfrequency range and high-voltage tests. The load hassustained tests at a voltage 35 kV at a repetition rate

The authors wishes to thank Korabelnikov Maximfor the improvement of the resistor manufacturing
techniques at BINP experimental workshop.

REFERENCES[1] V.I. Manilov, V.N. Shendrick. High current highvoltage resistor. Pribory i tehnicka experimenta.
Moskow, 1984, 4, pp. 112-114.
[2] A.I. Gerasimov. High-voltage low-impedance load
based on liquid resistors. Pribory i tehnicka
experimenta. Moskow. 1995, 5, pp. 73-78.
[3] A.V. Kiselev. Wire-bound resistor. Copyrightcertificate N SU 176972.
[4] B.I. Grishanov,Yu.G. Matveev.
Powerfulnanosecond loads. Pribory i tehnicka experimenta.
Moskow. 1976, 3, pp. 152-154.
[5] Yu.D.
Valjaev,B.I.Grishanov,G.S.Krainov,A.M.Molokoedov, V.F.Fogel. A powerful lowinductive high-voltage pulse resistor. Copyrightcertificate N SU 1809694.