Accelerator Power Supplies Division
Home Accelerator Power Supplies Division

Pulsed Power Supply Section Activity

Pulsed Power Supply Section is involved in the design and development of different pulsed power supplies and related technologies required for Septum and kicker pulsed Magnets used in Indus Accelerators. Pulse power sources to energise pulse magnets in accelerators are peculiar with specific pulse shape, high peak current, pulse-to-pulse repeatability and low jitter. Most of the pulse supplies deliver half sinusoidal current pulses in lumped magnet loads. Energy storage capacitor is used in pulse forming circuit in the sinusoidal current type pulse supplies. Some pulsed power supplies deliver trapezoidal type current pulse to magnet load. These supplies uses coaxial cable as Pulse Forming Network for the generation of current pulse. Silicon controlled rectifier switch or thyratron with low inductance assembly have been used as a switching device depending on voltage, current and fastness of the required pulse. Details of the developmental works are as follows-

Pulsed Magnet Power Supplies for Indus-1

The specifications of pulse power supplies required for booster (injection and extraction) and the Indus-1 SRS (injection) are listed in following table-

Parameters Booster Injection Kicker Booster Injection Septum Booster Extraction Kicker Booster Extraction Septum Indus-1 Injection Septum Indus-1 SRS Injection Kicker
Peak current1000 A5000 A2400 A6000 A6000 A5000 A
Pulse width13 μs200 μs0.1 μs200 μs200 μs1.2 μs (Rise) and fall time constant of 120 ns
Pulse ShapeHalf SineHalf SineTrapezoidalHalf SineHalf Sine
Jitter< 50 ns< 50 ns< 10 ns< 50 ns< 50 ns< 10ns
Load Inductance0.46 μH1.02 μH0.6 μH1.76 μH1.76 μH0.6 μH


The pulsed magnet power supplies have been developed to cater different pulse shapes requirements namely half sinusoidal, trapezoidal and damped sinusoidal rise and exponential fall. A brief description about the pulsers on the basis of pulse shapes is as follows-

Pulse Shape - Half Sinusoidal

The booster injection kickers, booster injection septum, booster extraction septum and Indus 1 injection septum magnets are energized by a pulse current of half sinusoidal shape. The pulse width varies in the range 13 micro seconds to 200 micro seconds and the peak current varies from 700 A to 5 kA for different magnets. These pulses are generated by discharging a bank of energy storage capacitors into the inductive load of septum magnet via a thyristor switch to form an under damped LCR circuit. Capacitor charging scheme for repeated charging of capacitor bank has been designed to deliver high degree of repeatability and stability for voltage of capacitor bank.

Booster injection septum
Booster extraction septum
Booster injection septum
Booster extraction septum


Pulse Shape - Trapezoidal

The booster extraction kicker magnet is energized by a pulse current of trapezoidal shape. The rise time of current pulse is 50 ns and the flat-top time is typically 70 ns. Coaxial cable of high voltage has been used as a pulse forming network. This cable is charged to a requisite voltage and discharged into the load by a Thyratron switch. A matched resistance of cable characteristic impedance has been used in series with load magnet.

Booster extraction kicker
Thyratron assembly
Booster extraction kicker
Thyratron assembly



Booster extraction kicker current pulse
Booster extraction kicker current pulse


Pulse Shape - Damped Sinusoidal Rise and Exponential Fall

The Indus-1 SRS injection kicker magnet is energized by a pulse current characterized by damped sinusoidal rise to peak and exponential fall from current peak. The rise time is 1.2 μs and fall time constant is 120 ns.

Indus-1 SRS injection kicker
Indus-1 SRS injection kicker


Pulsed Magnet Power Supplies for Indus-2

Output current waveform, for all the pulsed magnet power supplies for Indus-2 pulse magnets, is half sinusoidal.
  • Indus-2 Septum Magnet Power Supplies
  • Indus-2 Kicker Magnet Power Supplies
The specifications of pulse magnet power supplies required for Indus-2 are listed in the following table-

Parameters Thin Spetum Thick Septum Injection Kicker
Beam energy (MeV)700700700
Angle(o)2 and 3.6191.4
Peak current (A)5300850011000
Charging voltage (V)750100028000
Inductance (μH)0.952.70.84
Pulse shapeHalf sine waveHalf sine waveHalf sine wave
Pulse duration (μs)501003
Repetition rate (Hz)111
Amplitude stability1 x 10-41 x 10-41 x 10-3
Jitter (ns)10010010


Indus-2 Septum Magnet Power Supplies

The Indus-2 septum magnets (thin and thick) require half sine wave current pulse. These pulses are generated by discharging a bank of energy storage capacitors into the inductive load of septum magnet via a thyristor switch to form an under damped LCR circuit. The injection of bunches takes place at the peak (flat top) of the half sine wave. A bank of energy storage capacitors has been realized such that the series inductance of the circuit remains low. Eight RG-8/U cables form flexible connection link between power supply and magnet. The whole arrangement was made coaxial to reduce stray inductance.

Indus-2 thin septum
Indus-2 thick septum
Indus-2 thin septum
Indus-2 thick septum


Current waveform of  thick and thin septum
Current waveform of thick and thin septum


Indus-2 Kicker Power Supplies

In Indus-2 injection will be carried out by using horizontal multi-turn injection scheme. In this scheme a compensated orbit bump is produced and an electron beam is injected parallel to the bumped orbit via septum magnet. Injection will be carried out in the first long straight section, LS-1. The compensated bump will be produced by using four kicker magnets. A half sine wave type of current pulse has been fixed for Indus-2 kicker power supplies. Injection will take place around peak value of sinusoidal current. Base width of half sine current has been decided to be 3μs. Current peak required to give requisite deflection has been fixed to be 11 kA.

Injection kicker power supply
Injection kicker power supply

The required features for the kicker magnet power supplies are: 1) All the four kicker current pulses should have identical waveforms, 2) Kicker current pulse should have requisite degree of pulse to pulse current stability around peak, 3) Kicker current should reduce to a very low value in 1.5μs to 1.6μs from peak so as to reduce the compensated bump to zero, 4) Kicker current pulse should not go negative as it will disturb the stored beam. All the four kickers have identical mechanical arrangements for pulse generating elements. The peak of the current pulse is stabilized by keeping final stage capacitor voltage constant at a required value. Discharge switch, operating at 1Hz, has to pass a peak current of 11kA at a maximum di/dt of approximately 15 kA/μs which is reduced then by employing a magnetic assist. Time jitter requirement of the pulse is 10 nsec.

Other Development works

With a view to create upgrades on existing systems in terms of performance, specifications and use of newer and advanced technologies, Pulsed Power Supply Section is continuously working in R&D of pulse systems to create superior solutions to our present and future needs. Some of these developments are listed below.

Development of solid state switch based Pulsers

A series connected high voltage IGBT switch has been developed for pulsed power application using conventionally available devices of rating 1700V, 26A. Static and dynamic voltage sharing networks are used along with active clamp method for protection of series connected IGBT's. The gate drives are provided using fiber-optic cables which gives necessary galvanic isolation. The developed switch has a capability of switching 8 kV voltage and generating 1.6kA current with 3.5us pulse width at a PRR of 1 Hz. This development will lead to replacement of costly imported Thyratron switches upto certain voltage/current ratings using economical and commercially available devices.

Pulse power circuit along with IGBT driver stack
Pulse power circuit along with IGBT driver stack


1.6 kA peak current using  series switches
1.6 kA peak current using series switches

Modified Booster Injection Kickers for Booster up-gradation

Modified Booster Injection Kickers has been developed to deliver a pulse with 5 microsecond sinusoidal rise and 700 ns linear fall at 700A peak current for up-gradation of booster. Power supply uses a very compact pulse power circuit to meet stringent requirement of linear fall of current with high di/dt .

Modified Booster Injection Kickers for Booster up-gradation

Line side Active Filter

A 3 Phase line side active filter has been designed and developed in lab. This filter, when connected at the power supply end of a three phase non linear load, will supply the harmonic currents drawn by the load locally. Thus currents drawn from the a.c. mains remain nearly sinusoidal thereby reducing harmonic distortion on power lines. A three phase line side harmonic filter has been designed, developed and tested on a 400V, 3 phase, 50 Hz, 7.5 kVA well filtered diode bridge rectifier load to compensate the harmonic currents drawn by the rectifier.

Active filter for line current harmonic correction
Active filter for line current harmonic correction

25 Hz PRR capacitor charging power supply with twin phase shifted primary windings to achieve high charge transfer rate and high stability

A capacitor charging power supply (CCPS) was developed to charge bank of 50uF energy storage capacitor upto 2.5 kV in 35ms exhibiting a peak charging power of 4464 J/s at a repetition rate of 25pps. The High Voltage capacitor charging power supply consist of two identical full bridge resonant converters feeding to two primary windings of a transformer with rectified secondary connected to capacitor load. Topology selection is based on the fact that the series resonant converter with switching frequency fs, below 50% of the resonant frequency fr (fs <= 0.5 fr) act as a current source. Three phase controlled DC bus, twin phase shifted primary winding fed resonant converter and voltage comparator loop will ensure ± 100 ppm peak current stability.

Output transformer and IGBT drivers
Power supply front panel
Output transformer and IGBT drivers
Power supply front panel

Phase-Shift PWM Based Capacitor Charging Power Supply

A high voltage power supply has been developed for constant average current capacitor charging. PWM based charger has reduced peak current hence lowered losses. Phase-Shifted PWM has achieved soft switching without extra components. Constant average current capacitor charging has been achieved with a sensorless novel control scheme . A double two-switch bridge has enhanced reliability. Power supply has been developed to charge a capacitor of 50uF to 2.5 kV at a pulse repetition rate of 25Hz.

Assembled power supply
Assembled power supply

Pulse Power Supply For Transmission Line Type Kicker Magnet

A 25 Hz kicker power supply has been designed and developed to test a 6.25 ohm transmission line type kicker magnet for technological development for perceived future needs. This power supply delivers a 2kA trapezoidal current pulse with a rise, fall and flat top time of 100ns, 100ns and 500ns respectively. The current pulse is generated by discharging a pulse forming network into matched transmission line kicker magnet. A high voltage thyratron CX1666 is used as a switch. The design of PFN was a critical issue from the fabrication point of view due to smaller impedance and faster rise time requirement. We have dealt with the specific issues related to the pulse charger, design of pulse forming network and thyratron assembly for achieving faster rise time of current pulse.

Pulse Power Supply For Transmission Line Type Kicker Magnet
Pulse Power Supply For Transmission Line Type Kicker Magnet
Developed high voltage pulse power supply and its schematic

A 60kV high voltage pulse power supply has been designed and developed to test a 12.5 Ω transmission line type kicker magnet for technological development for perceived future needs. This power supply delivers a 2kA trapezoidal current pulse with a rise, fall and flat top time of 70ns, 100ns and 70ns respectively. The current pulse is generated by discharging a charged pulse forming network into matched load. A high voltage thyratron CX1836 is used as a switch. The design of PFN, low inductance thyratron assembly and termination box at 50 kV were few critical issues for faster rise time requirement. We have dealt with the specific issues related to the pulse charger, design of pulse forming network and thyratron assembly for achieving faster rise time of current pulse.

60kV pulse power supply for fast rise current pulses
60kV pulse power supply for fast rise current pulses


For more information, please contact:
Shri Yash Pal Singh
Head, Pulsed Power Supplies Section
Phone: +91-731-248-8045
Email: ysp(at)rrcat.gov.in
Best viewed in 1024x768 resolution