How I Built My First Plasma Physics Experiment

The year was 1964. My role as a lecturer at Athanasius College, Kothamangalam, was beginning to feel like a trap. I could see the trajectory ahead: aging, taking tuitions, marrying, building a house, and achieving a comfortable affluence — all while being unable to do what I truly craved: research. The “bug” had bitten me during my student days in Trivandrum, where I would listen, spellbound, to post-graduate physics students debating modern physics, even if I understood barely half of what they said.

Determined to pursue research but unsure of the path, I began writing to heads of departments across various universities. When those inquiries met with silence, I followed the advice of friends: “Go there and talk to them.” I embarked on a Bharatdarshan.

My journey took me from Madras to Calcutta, and then toward Delhi. Allahabad and Patna left me unimpressed, but having heard about Aligarh Muslim University from my friend O. M. Mathew, I decided to stop there. I walked directly into the office of Prof. Rais Ahmed, who had recently returned from England to head the physics department. He was surprised when I introduced myself and declared my intent to do research. He grilled me with general questions, which I answered well. When I told him I had saved money from my Kothamangalam days and was prepared to work without immediate financial support, I saw him soften. He eventually secured a Ministry of Education scholarship for me — a sum of Rs. 250, though it was notoriously irregular, with months often passing between payments.

The physics department at Aligarh had, by then, lost the luster of its glory days; the groundbreaking work on cosmic rays led by Prof. P. S. Gill and spectroscopy by Prof. Putcha Venkateswarlu had concluded. Prof. Rais Ahmed, who had studied speech recognition in England, was attempting to rebuild the department’s research base. Aware of the emerging work at Oxford on ionized gases, he encouraged me to take a risk and pioneer experimental work in plasma physics.

Impulsive as I was, I accepted the challenge, unaware of the immense risk involved in starting from scratch in a department with no established faculty or precedent in the field. Prof. D. C. Sarkar, who had previously worked in plasma physics at Varian Laboratories in the U.S., was assigned as my guide. Looking back, those were the ideal conditions for an independent experimentalist: there was no one to tell me what could or could not be done.

My thesis focused on simulating the “Luxembourg effect,” a phenomenon where the powerful Radio Luxembourg modulated the ionospheric plasma, causing weak European stations to inadvertently carry its signal. I immersed myself in the literature, particularly Tellegen’s experiments on ionospheric cross-modulation.

Dr. K. A. George from the Tata Institute of Fundamental Research (TIFR) provided the crucial guidance on building the high-power radio frequency equipment I needed. I designed a simple push-pull RF oscillator using World War II-era vacuum tubes foraged from the Electrical Engineering department. With no data sheets available, I had to generate the current-voltage characteristics myself. The setup used a modulated RF discharge plasma as the medium through which an X-band microwave signal propagated, picking up the modulation.

I scraped together the microwave source, transmission lines, and power supplies from the remnants of Prof. Putcha Venkateswarlu’s laboratory, as he had recently departed for the new IIT Kanpur. My fellow research scholars — Subhas Chandra, Yogendra Kumar, and Rajeshwari Prasad Mathur — were instrumental in helping me navigate that unfamiliar terrain. Thesis work proved to be a masterclass in everything from glassblowing to machining. I received my degree in 1969.

I realized the experiment would be stronger with a theoretical model to estimate modulation transfer as a function of frequency. I observed that the transfer increased up to 100 Hz, then declined. Prof. Sodha, the eminent plasma physicist from IIT Delhi, was visiting at the time; he sat me down and helped me work out a rudimentary theory to estimate this effect.

My viva voce was held in the office of Prof. Nagchowdhury, a former Director of the Saha Institute of Nuclear Physics and a member of the Planning Commission. Prof. Sodha was my other examiner. I found myself in hot water when I suggested that the peak in modulation transfer at 100 Hz might be due to a resonance of acoustic waves excited by the modulation of electron temperature. The examiners rejected this vehemently.

The same year I received my degree, new posts opened in the department. Prof. Rais Ahmed invited me to apply, and I became a lecturer.

Prof. Rais Ahmed held modern, progressive views on education. He instituted a unique accelerated B.Sc. course for gifted students and served on panels advising Prime Minister Indira Gandhi. Through his mentorship, I began to understand that science was not merely about creating knowledge, but about channeling and shaping society. I started reading the Bulletin of the Atomic Scientists and other journals on science and society.

The possibility of acoustic wave excitation in plasma stayed with me. I secured a CSIR project to investigate it further. By this time, work on the theory of acoustic wave generation in plasma by Uno Ingard at MIT had appeared in Physical Review Letters, and we were able to publish a paper confirming the observation of this effect in our laboratory plasma.

While I found teaching deeply engaging and discovered I had a knack for it, it soon became clear that the department offered little room for growth, especially with the impending departure of Prof. Rais Ahmed to become Vice-Chairman of the UGC. Funding was perpetually scarce, and my attempts to secure a post-doctoral fellowship in the U.S. were not bearing fruit.

Then, Prof. Bimla Buti visited. She asked if I would like to join the Physical Research Laboratory (PRL) in Ahmedabad, which was planning to launch an experimental program in plasma physics. I jumped at the opportunity.

Looking back after all these years, I realize that the experiment I set up at Aligarh was, in truth, the first modern plasma physics experiment in India. Until then, work on ionized gases at Allahabad and Banaras had been confined primarily to ionization phenomena and the electrical breakdown of gases.