People ask me about my specialization as a Physicist.  I believe physics is the mother of all sciences; therefore, I never limited myself to physics alone.  I applied physics concepts to learn many other subjects.  While developing Yog Science, I studied Neuroscience, Physiology, Molecular Cell Biology, and Psychology.  I believe that if a person can understand the concepts of Physics, he is capable of understanding all the subjects.  While studying particle Physics and quantum electrodynamics at Delhi University, I wanted to become a theoretical physicist, and I was fascinated by wave-particle duality.  By then, I realized that physics is about the behavior of matter, not its nature; therefore, I wanted to pursue research in this field.

My second favorite subject is Electronics, but I never considered a career in it; it was just a hobby.  My father was a technician at the Milk Pasteurization Plant, and he used to repair the plant’s circuit boards.  So I had access to many electronic components, such as relays, coils, and super-enameled copper wires.  Therefore, I got an opportunity to make small projects for a science exhibition at school at the age of 13.  After joining Bhabha Atomic Research Center (BARC), I worked in the field of Mössbauer spectroscopy.  In the year 1977, it was a relatively new field of research, and a commercial setup for Mössbauer spectroscopy was not available.  I got the opportunity to improve a crude setup that was already working.  The data acquisition process was very slow, and it used to take weeks to collect a sizable amount of data before analysis was possible.  I used the spare time to develop a microprocessor-based data acquisition system for this setup.

Then I participated in a project to develop a model of a magnetically levitated train with linear-motor traction.  In this motor, one component of the magnetic force was used for levitation and another for the traction.  I developed the control system to power the electromagnets by sensing the magnets’ position.  I published a joint paper on this work in IEEE Control and Instrumentation.  Later I used the idea of switching a linear array of electromagnets to develop a circular motor.  This was perhaps the first brushless DC motor driven by a power control circuit. 

After completing this project, I worked in gamma-ray astronomy.  A burst of Gamma rays from outer space falls on the entire Earth and generates visible light through interaction with the atmosphere.  To detect the light emitted by gamma-ray bursts, at least three photomultiplier tubes are installed in three distant countries.  If three stations detect a light pulse simultaneously, they identify it as a gamma-ray pulse.  The station clocks were manually synchronized using a common time signal broadcast by a radio station.  (Atomic clocks used to send time data on mobile networks were not available at the time).  Manual synchronization introduced a fraction-of-a-second error in the station’s clock. Therefore, I developed a circuit to automatically synchronize the clock with millisecond accuracy.  I also completed theoretical work in this field that eliminated the need for three stations.  I calculated a profile of the light pulse received at the photomultiplier tube.  I divided the sky into infinitesimally thin annular rings whose radius increases continuously.  The light intensity was highest at the center, just above the photomultiplier, and decreased as we moved to outer annular rings.  In this way, I calculated the exact shape of the light pulse produced by gamma-ray bursts.  The photomultiplier is a very sensitive device that detects all sorts of light pulses generated in the sky, such as those from the trail of a meteoroid.  But the light pulse generated by the Gamma ray can be identified by its specific shape, which I calculated.

In 1987, I came to RRCAT (then CAT) to work on a project, Indus-I, which is a Synchrotron Radiation Source (SRS).  In this project, electrons are injected into an electron accelerator called the booster ring to attain an energy of 700 MeV.  The electrons are then extracted from the booster ring and injected into a storage ring, where synchrotron light is generated at the bends in the electron trajectory.  This operation required a momentary deflection of electrons by electromagnets.  I developed pulsed power supplies to generate a magnetic-field pulse when electrons reached the magnet.  In one magnet, the peak current requirement was 5000A.  This required a robust mechanical design to counter the huge repulsive force from the current.  In another power supply, a current of 1200A was switched in 30 nanoseconds.  The peak-current stability requirement was in ppm, and the time accuracy needed to synchronize the pulse with the electron position was a few nanoseconds, which was a challenge 25 years ago.  The pulse supply generated significant electromagnetic interference (EMI) that needed suppression to prevent malfunctions in other subsystems.

I also developed a Beam Position Monitoring system to monitor the position of an electron beam in a vacuum chamber.  I calculated the signal produced by the electron beam at the sensing electrodes.  After that, I designed and developed front-end electronics; this required designing very high-gain amplifiers to amplify signals below 1 microvolt and storing the signal in flash memory using a very fast ADC.