I met Predhiman Kaw for the first time in 1972 when I visited the Physical Research Laboratory (PRL) to give a talk on my work on plasma mediated interaction between strong electromagnetic fields. When I joined PRL later in the same year, I had the task of setting up a plasma physics laboratory from scratch. Over the years, this activity grew and developed into the Plasma Physics Programme in 1982, funded by the Department of Science and Technology to initiate fusion research in India by building the Aditya tokamak. In 1984, this transformed into an autonomous Institute for Plasma Research which, in addition to the fusion experiment, blossomed into many activities in plasma physics, fusion technologies and applications. The Steady-State tokamak programme started in the mid-1990s, was another quantum jump in scope and extent. In 2008, we saw India joining the ITER and the Institute setting up a Domestic Agency for overseeing the Indian contributions to ITER. My association with Predhiman continued through all these transitions. I have seen him in many roles; as a great plasma physicist, as a powerful motivator, as an interpreter with great clarity of thought, as a person with deep philosophical and spiritual moorings, as a clever and nuanced strategist, and above all as a person with a grand vision of the role of India in fusion and plasma physics. Predhiman was an outstanding scientist with a broad range of research interests and a prodigious research output spanning over 389 papers in international journals. His early work at Princeton during 1967–71 resulted in seminal contributions to nonlinear problems connected with laser-plasma interactions. From 1971–75, while he was at PRL, Predhiman extended the theory of parametric instabilities to magnetized plasmas. Prof. Kaw received many honours and awards during his illustrious career, starting with the Indian National Science Academy’s Young Scientists Award of 1974. In 1985, the Government of India honoured him with the Padma Shri award; in 1986, he received the SS Bhatnagar award. Recently, he was named the 2015 laureate of the Subrahmanyan Chandrasekhar Prize for “outstanding contributions” in the field of plasma physics by the Association of Asia Pacific Plasma Physics Societies. We collaborated on an experiment to study non-neutral plasma clouds. Together we thought up a novel toroidal device in which a central current-carrying conductor along the major axis of a fat cylinder would give us a very low aspect ratio system. Electrons were injected into this device as the toroidal magnetic field was ramped up. Except that the rising magnetic field would carry the electrons towards the minor axis, we had no prior knowledge of how the system would behave. We analysed the resultant electron cloud using potential probes and found that we had formed a toroidal cloud of electrons hugging the central conductor and proved that an equilibrium does exist. The paper we wrote was published in the Physical Review Letters and was the first experimental plasma physics paper to appear in that journal from India. Predhiman’s perceptive understanding of the electron cloud dynamics played a crucial role in developing a coherent knowledge of the strong toroidal effects in the behaviour of electrons in such a system. Furthermore, we brought out the strong complementary aspects between current-carrying neutral plasmas and charged non-neutral plasmas, and this was substantially due to Predhiman’s deep knowledge of plasma physics. Predhiman strongly believed that science should be pursued with complete freedom. When we started to plan the IPR buildings, we had endless discussions on how the buildings should reflect this. The buildings do give one a sense of liberation. The wide corridors, openness to the sky and the surroundings, and oneness with nature are all embodiments of this conviction. It also turned out that we were rather free with the budget, which indeed raised many beaurocratic eyebrows. Predhiman’s unique capacity to absorb knowledge from all sources was evident when we built Aditya. Together we went on a grand tour of India to visit industries and assess how they could contribute to the engineering of the Aditya Tokamak, which was fairly ambitious as a first fusion device. He had a childlike curiosity to understand how large mechanical components would be machined, how high current copper windings would be made for a transformer, how precision welding was done etc. As a result, he acquired an engineering knowledge in a few months that every experimentalist learns over a lifetime. The fact that Aditya went into operation, despite many teething problems like the failure of the main power transformer etc., is a testimony to his skill in growing a team of experts and making them work together and systematically solving problems. After Aditya got into routine operation, I became interested in exploring commercial applications of plasmas. Although there were criticisms that this was a deviation from the original charter of the institute, Predhiman was wholeheartedly in support of pursuing this path. This completely complies with his belief that any interesting idea should be pursued with full vigour. We soon established a Plasma Processing Programme, which evolved into the Facilitation Centre for Industrial Plasma Technologies. The programme had some unique aspects that one does not have to worry about in basic science research. Some examples are the necessity for it to be relevant to the industry, the fact that it can make or lose money in its commercial exploitation, the contractor-client relationship with industries, etc. So, the rules for running this programme had to be developed and learnt as the programme grew. The fact that it was the first time in India that a basic research institute ventured into a commercial application programme also meant that we could not learn the rules from prior experience. Predhiman again played a crucial role in ensuring that the learning process was sound and the practices conformed to good management principles. In India, research institutions are well funded. Money is generally not a problem in pursuing research; the lack of ideas and human resources are. The situation in Indian universities is the converse. Predhiman has been very sensitive to this imbalance and has taken many initiatives to correct this. He convinced the Department of Science and Technology to establish a programme called Satellite Research Projects for funding universities in plasma sciences research. This and its later forms, such as the Cross-Disciplinary Projects in Plasma Sciences, have been instrumental in nucleating research in plasma physics ad applications in many universities, some of which have grown to large centres. These are the forerunners of our present and ambitious National Fusion Programme, where universities and educational institutions are funded rather well to take up fusion-related research and development work. We pursued many ideas in discussions and sometimes in experimental exploration. The Thursday Circle was the result of one such discussion. The idea was to have meetings discussing issues relevant to society and life. This was put into practice at IPR for quite some time. Once while visiting BARC, we discussed converting physical movements like walking or random movements of our arms into electrical energy. We also set up small experiments to pursue this. I would also like to say something about the important role played by Predhiman in ensuring that India became a member of the ITER project. This involved, in one part, a campaign within the Indian science establishment and concerned ministries to convince them of the importance of fusion technology from a long-term perspective of India’s energy security. There was an equally important aspect of convincing the existing ITER partners of India’s potential to be an essential contributor to the ITER programme. Predhiman was the de facto leader of the Indian team, which participated in the presentation of the formal proposal for Indian membership in ITER and the negotiations in Jeju. His persuasive skills were very evident in these meetings. Predhiman’s critical role in giving clear direction to ITER in its early years is worth mentioning. He was the chairman of the STAC, the ITER’s Science and Technology Advisory Committee. I see STAC as the conscience keeper of ITER, making sure that there is no compromise in the final scientific and technical objectives of ITER. However, to ensure this in ITER, where the politics is even more convoluted than the technology, is a Herculean task. Nevertheless, there is a full realization within the ITER system that Predhiman did a fantastic job resolving many complex STAC issues and helping ITER finalize its technical specifications.
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