Scientific Accelerator Division

The CLIC Pre-Damping Rings (PDR) and Damping Rings (DR) need kicker systems to inject and extract
the beam: these kicker systems require power modulators. The damping rings are necessary to achieve
the very low emittance for the particle beam. To avoid beam emittance increase, the DR kicker
systems must provide extremely flat, high-voltage, pulses – the requirements for ripple and droop
exceed the specifications of any known existing system. The specifications for the DR extraction
kickers include 160 ns (2 GHz specifications) to 900 ns (1 GHz specifications) duration flat-top
pulses of ±12.5 kV, with a combined ripple and droop of not more than ±0.02 % (±2.5 V). The DR
extraction kicker system consists of a stripline kicker and two pulse modulators. The
specifications for the modulators call for pulses with 160 ns or 900 ns flattop duration of ±12.5
kV and 305 A, with ripple of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising
approach to meeting the specifications because analogue modulation methods can be applied to
control the output waveform. A 3.5 kV prototype adder, which utilizes Finemet magnetic cores to
allow up to ~1 µs pulse duration, has been tested at CERN: a measured relative flat-top stability
of ±0.04 % (±1.0 V) has been demonstrated at 2.4 kV output, for ~900 ns flat-top duration, and
±0.01 % for (±0.3 V) for 160 ns flat-top duration.

The design of a full-power prototype, 20-layer, inductive adder has been finished. New Printed
Circuit Board (PCB), which allow up to 12 parallel capacitors and semiconductor switched per
half-layer, have been designed and procured. Mechanical parts for the 20-layers of the full-scale,
12.5 kV, prototypes have been received. Finemet magnetic cores have also been received for the
full-power prototypes. Assembly of the first full-scale, 20-layer, 12.5 kV prototype inductive
adder has commenced at CERN and tests and measurements will commence in the near future.

ALBA-CELLS, with the support of CERN, will be responsible for the ongoing tests, measurements and
research and development, of the full-power inductive adder.
The works will be carried out mostly at CERN premises, where staff from ALBA-CELLS will develop the
project under the supervision of Mike Barnes at CERN.

The main goals are to:
• Demonstrate operation of first full-power, 20 layer, inductive adder at voltages up to +12.5
kV and current levels of at least 300 A:
o Measure stability and repeatability;
o Tailor the output waveform, using analogue modulation, of the prototype inductive adder
to achieve the waveform required for the DR extraction stripline kicker;
• Demonstrate operation of first full-power, 20 layer, inductive adder at voltages up to -12.5
kV and current levels of at least 300 A
o Measure stability and repeatability;
o Tailor the output waveform, using analogue modulation, of the prototype inductive adder
to achieve the waveform required for the DR extraction stripline kicker;
• Assemble the second full-power prototype inductive adder with 28-layers.
o With 20 of the 28 layers operating demonstrate at voltages up to +12.5 kV and current
levels of at least 300 A:
? Measure stability and repeatability;
? Tailor the output waveform, using analogue modulation, of the prototype inductive
adder to achieve the waveform required for the DR extraction stripline kicker;
• Remove 8-layers from 28-layer inductive adder. Connect the two 20-layer inductive adders to
the striplines, with opposite output polarity. Demonstrate simultaneous operation of the
inductive adders at voltages up to ±12.5 kV and current levels of at least ±300 A:
o Measure stability and repeatability;
o Tailor the output waveform, using analogue modulation, of both prototype inductive adders
to achieve the waveform required for the DR extraction stripline kicker.
• Demonstrate long-term, reliable, operation of the two inductive adders;
• If ALBA-CELLS can measure the pulse performance of the inductive adders, ship the adders to
ALBA for tests and measurements, together with striplines, in the beamline. Or else,
demonstrate operation of a 28-layer inductive adder at voltages of up to ±17.5kV.