People ask me about my specialization as a Physicist. I believe that Physics is the mother of all sciences, therefore I never limited myself to Physics only. I applied the concepts of physics to learn many other subjects. During the development of 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 in Delhi University I wanted to become a theoretical Physicist and I was fascinated by wave-particle duality. I realized by that time that Physics is about the behavior of matter and it is not about the nature of matter, therefore, I wanted to pursue research in this field.
My second favorite subject is Electronics but I never thought about a career in Electronics and it was my hobby. My father was a technician of the Milk Pasteurisation Plant and he used to repair circuit boards of the plants. So there were many electronic components available to me 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 Centre (BARC), I worked in the field of Mossbauer Spectroscopy. In the year 1977 it was a relatively new field of research and commercial set up for Mossbauer 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 the analysis could be possible. I utilized the spare time to develop a microprocessor- based data acquisition system for this set-up.
Then I participated in a project of developing a model of magnetically levitated train with a traction by linear motor. In this motor one component of magnetic force was used for levitation and another for the traction. I developed the control system for powering the electromagnets by sensing the position of magnets. A joint paper on this work was published 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 was associated in the field of Gamma Ray Astronomy. A burst of Gamma rays from outer space falls on the entire earth and it generates visible light by interaction with the atmosphere. In order to detect the light emitted by Gamma ray bursts at least three photomultiplier tubes are installed in three far off countries. If a light pulse is detected simultaneously at three stations then it is identified as a Gamma ray pulse. The clock of the station was manually synchronized by a common time signal broadcast by a radio station. (The atomic clocks that are used to send time data on mobile networks were not available at that time). The manual synchronization introduced an error of a fraction of a second in the clock of the station. Therefore, I developed a circuit to synchronize the clock automatically with an error of a millisecond. I also completed a 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 intensity of light started at the center just above the photomultiplier was maximum and intensity decreases as we move 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 which detects all sorts of light pulses generated in the sky such as one generated by the trail of a meteoroid. But the light pulse generated by the Gamma ray can be identified by its specific shape calculated by me.
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 booster ring to attain an energy of 700 Mev. Then the electrons are extracted from the booster ring to inject into a storage ring where the synchrotron light is generated at the bends of electron trajectory. This operation required a momentary deflection of electrons by electromagnets. I developed the pulsed power supplies to generate a pulse of magnetic field when electrons reach the magnet. In one of the magnets peak current requirement was 5000A. This required a robust mechanical design to counter the huge force of repulsion due to the current. In another power supply a current of 1200A was switched in 30 nanoseconds. The stability requirement of peak current was in ppm and time accuracy to synchronize the pulse with the position of electrons was a few nanoseconds which was a challenge 25 years ago. All pulse supply generated huge electromagnetic interference (EMI) that needed to be suppressed in order to avoid malfunction of other subsystems of the project.
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 of amplifiers of very high gain to amplify the signals of less than one microvolt and storing the signal in flash memories using very fast ADC.
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