I was recently invited to give the Kuriakose Mar Gregorios Memorial Lecture at a college in Pampady, a small town near Kottayam. I discussed the role of ideas in innovation, the concept of the combinatorial evolution of innovations from earlier innovations, the environments where innovation happens, the concept of ‘The adjacent possible’ and the Indianised concept of Jugaad innovation. At the end of the talk, the students wanted to know some examples of innovation which I had initiated. That triggered a stream of thought related to a phase in my life where inventions and innovations were an integral part of my professional existence.
Scarcity is the mother of innovation. In the early days of our setting up the Plasma Physics programme at the Physical Research Laboratory in Ahmedabad, a persistent problem was the non-availability of critical laboratory parts required to do advanced plasma physics experiments because of strict import restrictions and lack of adequate financial resources. We had to find ways to improvise and invent out-of-the-box solutions.
For example, we devised vacuum RF couplers with Amphenol connectors embedded in an epoxy cast. High-voltage feed-throughs were made using outsized O-rings forming electrically floating vacuum flanges. Sinusoidal voltage bias on a Langmuir probe ramped it to create current-voltage characteristics. We learned to trigger vacuum spark gaps with Bostick plasma guns made from two wires embedded in a plastic stub. We learned that a piece of paper with pencil scratches would act as an overvolted surface discharge source to trigger a coaxial plasma gun. Finally, we even learned to create high-voltage pulse trains with nanosecond rise time by using a double-Blumlein pulse-forming line with discarded Coaxial cables and rotating spark gaps.
Another innovation happened in connection with the development of plasma nitriding, a surface engineering process for hardening steel by incorporating Nitrogen into the steel lattice from NH radicals extracted from an abnormal glow discharge in a Nitrogen-hydrogen mixture. The workpiece to be hardened acts as the cathode of the abnormal glow discharge. This type of discharge operates near the glow-to-arc transition, with small arcs getting initiated at the work surface. The arcs can damage the surface of the workpiece and have to be prevented.
The arc initiation happens after a time delay of a few tens of microseconds after the full voltage for the glow discharge is applied to the workpiece. So the technique for preventing the arc transition is to operate with a train of voltage pulses instead of a steady DC discharge voltage. The power is turned on for a few tens of microseconds and then turned off, the sequence repeating for the full nitriding cycle, typically a few hours. The switching is done by power transistors.
Power supplies are the most expensive component of a plasma nitriding reactor. Pulsing at a 50 per cent duty cycle means that the expensive system is used for only half of the operating time. We wondered whether we could switch the power supply to a second nitriding workload when the first load is off. Then the power supply would be used for its full duration, although each load is energised for only half of the time. Full-time utilisation is the optimum exploitation of expensive capital equipment and impacts the economics of plasma nitriding. We implemented this idea in a prototype machine but did not develop it for commercialisation.
Another creative idea sprang up during the development of a plasma pyrolysis system for medical waste. We use a device called a plasma torch to create very high-temperature plumes of plasma. Temperature is as high as ten thousand degrees, which promotes fast pyrolysis of organic waste. It is an electrical arc between two electrodes, extracted out of the electrode region using a high-speed flow of Nitrogen gas. When the plasma plume from the torch falls on organic waste, it gets sublimated and converted into gases such as Carbon Monoxide and Hydrogen. This is burned in a vertical furnace and the products are cleaned and released into the environment.
The CO + H2 mixture, produced during the pyrolysis of any organic waste is the Syngas, which contain chemical energy. If this is purified, compressed and collected, it can be commercially used as an energy gas which can either burn or power internal combustion engines. This is the basis of the waste-to-energy concept in plasma pyrolysis.
But if the Torch uses Nitrogen, the Syngas get mixed up with Nitrogen. Nitrogen must be removed because it cannot burn. The separation is a costly process. However, if the pyrolysis product gas is collected, cooled and recirculated in the torch, there will be no dilution of the product gas with Nitrogen.
This invention also made the pyrolysis process more efficient. It also dispensed with the expensive Nitrogen cylinder for the operation of the torch. We got a patent for this, “Plasma Torch with Endogenous Gas Source”.
A very innovative application we developed was in response to an enquiry we received from the Department of Science and Technology on the possibility of using plasmas to clean the Carbon soot deposited on the walls from the oil lamps used in temples. We found a NASA invention of producing atomic Oxygen in a high-voltage streamer discharge. The atomic Oxygen would react with Carbon in the soot and convert it into Carbon Dioxide. We even packaged the Atomic Oxygen generator inside a hairdryer, to demonstrate to DST officials the ease of using it.
A truly innovative idea came up when we were in the process of developing a Teflon-like super-hydrophobic (water-repellant) coating on metal surfaces. The precursor for the plasma polymerisation process was Carbon Tetrafluoride gas, which was not available for purchase in small quantities. We hit upon the idea of pyrolyzing waste Teflon to generate the gas, with which we could synthesize the Teflon coating.
The seed of an idea which was born while discussing with my friend Abhijit Sen on scaring away pigeons which used to foul the terrace of his palatial home in Ahmedabad got muscles and body with further thinking during our travels to the office in shared transport. Energy storage capacitors discharged through atmospheric pressure overvolted spark gaps give a loud bang, enough to scare away the pigeons, but were considered dangerous for use in a domestic setting. A potentially successful idea was a dispenser which would drop clumps of quicklime or Calcium Oxide into water with random periodicity. The resulting slaking reactions would cause explosions which we thought would scare the pigeons away. We never built this.
Innovation is a basic human instinct. The requirement to adapt physically and functionally to the surrounding environment drove us on the evolutionary path for millions of years in the past. Innovation is the remnant of that process where we modify our environments to suit us.
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