Updated: Oct 11, 2022
The Plasma Physics Programme had been set up at the Physical Research Laboratory in 1982 by the Department of Science and Technology, Government of India under the Intensification of Research in High Priority Areas. Its charter was to initiate India into magnetically confined high-temperature plasma research by building a tokamak. By 1986, the Plasma Physics Programme moved into a new campus in Bhat village and was upgraded into the Institute for Plasma Research. In 1989, the tokamak, ADITYA, was commissioned and went into a phase of routine operation.
For me, it was a time to look at new opportunities. Plasma physicists worldwide were exploring novel ideas to apply their knowledge of plasma physics to material processing, environmental remediation, and a host of exotic applications. Using plasmas for near-term industrial applications appeared to be very timely. The rich experimental knowledge base created over two decades of producing and manipulating plasmas to support research at the Physical Research Laboratory and the Institute for Plasma Research was a substantial capital. The decision resonated with the international perspective that plasma science offers unique and novel opportunities in high-energy-density and high value-added material processing.
Plasma assisted manufacturing exploits plasma as an industrial tool. Plasma can respond to external electromagnetic energy fields and transport energy. The fluid properties are enhanced by the particles setting up internal self-consistent electric and magnetic fields, resulting in collective effects like flows, waves, instabilities, and self-organization. Each species may have independent energy distribution, not necessarily in equilibrium with other species. The internal energy is composed of thermal, electric, magnetic and radiation fields, whose relative magnitudes allow the plasma state to exist in ample, multi-dimensional parameter space.
Plasma processing was surging internationally with the realization that the fourth state of matter offers unique opportunities in material processing. Properties like high chemical reactivity, microscopic electric fields, sheaths, radiation, and particle flux mediate plasma processing. Plasma-based manufacturing integrates the plasma-material interaction phenomena with the manufacturing process. The technology adds value to conventional materials and makes new types of materials and processing techniques possible. The characteristics of both the equilibrium and non-equilibrium plasmas can be exploited for commercial uses. Comparable international and indigenous capability stature in this field was a rare opportunity for leadership in an emerging field.
A proposal to start a research programme on applying plasma science to near term industrial applications relevant to India was approved by the IPR Council in the early 1990s. The programme had to be industry-driven to make it agile and responsive to rapid changes and focused on a few thrust areas where the immediate impact would be possible. Financial self-reliance was a goal from the beginning. There were no pre-existing models of similar activity in essential research organizations in India. So, the business plan evolved and matured along with our activities.
The Plasma Processing Programme had some unique features not encountered in basic research. The necessity for it to be relevant to industry, the fact that it can make or lose money in its commercial exploitation, the contractor-client relationship with industries etc., are some examples. It was the first time in India that a basic research institute ventured into a commercial application programme. So, there were no precedents from earlier experience.
The first foray was into plasma nitriding because of the interest shown by several industries. This is a process in which Nitrogen is incorporated into the steel matrix to increase hardness. Along with Chitra Natarajan, I looked at the specifications of the state-of-the-art systems. We then took a conscious decision not to build them, but to start an accelerated trek through the various phases of its development. So, we started with conventional DC glow discharges stabilized with external ballast resistors. Later, we incorporated pulsed DC. The prototype was a cold wall furnace with only plasma heating. Heat shields were added to minimize heat loss. By allowing an insulated liner to reach elevated temperatures, we increased thermal efficiency and temperature uniformity. By actively heating the vacuum vessel or the liner with a heating element, we obtain the auxiliary heated hot-wall reactor. The heating of the workpiece is obtained by the combination of plasma heating and radiation and convection heating by the wall. During this time, we also added automation and computer control to build state-of-the-art systems.
It is easy to fall into a false sense of confidence of knowing the technology of plasma nitriding when you see the familiar glow around an industrial component. The technology is in the unglamorous details. I had prepared a long list of questions for which we needed credible answers before we could say that we have mastered nitriding technology. How exactly do we distribute the workpieces so that temperature is uniform or how we can control the microstructure are two of such questions.
Plasma Nitriding became the first technology to be transferred to industry. In addition to this, we set up a job-shop to do nitriding of high-value component like plastic dyes etc. on a commercial basis.
The zircon dissociation was our first foray into thermal plasmas and plasma torches. This happened when C S Gupta, an industrialist running the CS Zircon Products Pvt Ltd, in Himachal Pradesh approached the Department of Scientific and Industrial Research with a request to support them to revive a process patented by Ion Arc after the termination of the lapse of the patent. The plasma route was economically viable in Himachal Pradesh because of the very low cost of electricity. DSIR approached us to help the company through the phases of process development and optimization. CS Zircon copied the patent, which had lapsed by that time and rigged up a reactor including the plasma torch. The torch had a thermionic tungsten cathode and three graphite anodes. The anode tips would sublimate during operation and were driven forward by three independent motors. The zircon sand as fed through an opening near the cathode. The particle would heat up while passing through the plasma plume and the silica layer would melt and form a sheath around each particle with the zirconia at the core. Light chemical etching would remove the silica.
Plasma processing got a big boost when it became part of the Surface Engineering initiative of the Department of Science and Technology when Prof. P. Rama Rao was the Secretary, DST. This programme opened collaboration with German Institutions. I was a member of a delegation that visited the Fraunhofer Institutes to set up programmes of institutional collaboration. We got partnered with the Technical University of Clausthall and the Nuclear Institute in Dresden on plasma ion implantation, which involved visits and exchange of research personnel. In addition to providing commercial-scale implantation service to industries, we were able to sell a pulsed high voltage system for plasma ion implantation to the Technical University.
I felt an urge to communicate the excitement of all this new knowledge to industries. The first issue of the Plasma Processing Update came out in 1994. The early issues were written almost entirely by me. With time, came new enthusiasts from among the new staff. The fact that it has survived all these years is a true indication of the passion of the practitioners of plasma processing in their work and their commitment to engage with the industry.
I also started planning to write a book discussing the versatility of the plasma state of matter as an enabling tool for industrial, manufacturing, environmental and engineering applications. Conceived as an introduction to the technology, practice and the commercial aspects of plasma-enabled material processing and manufacturing, the book was meant for the agents of change in the present-day society, students, professionals, entrepreneurs. The book, titled “Plasma Sciences and the Creation of Wealth” was published in
2005 by McGraw-Hill, India. Originally published at http://pucadyil.blog on April 17, 2021.