FUSION | INDIA
India’s activities in nuclear fusion
Fusion power is seen as an important part of India’s long-term energy supply. The government hopes to build domestic demonstrators by mid-century. Saurav Jha reports
IN JANUARY 2020 INDIA’S FIRST Tokamak, the Aditya, completed 30 years of safe operation. Those thirty years saw India making steady if limited investments in nuclear fusion research. Apart from creating some tokamak ‘assets’ such as the Aditya and the Steady-State Superconducting Tokamak (SST-1), India’s fusion-related activities have been heavily focused on domestic sub-systems development, given the country’s history of being subject to abrupt technology denials. Domestic efforts in sub-systems development and basic research related to advanced tokamaks since the 1980s have positioned India to be a major partner in the International Thermonuclear Experimental Reactor (ITER) project, which is expected to yield the world’s largest tokamak-based reactor. India’s Department of Atomic Energy (DAE), which believes that fusion power is an important component of the country’s long-term energy security, aims to fund a few demonstrators of its own with a view to commence building two 1000MWe grid-connected fusion reactors by 2050. The key DAE-supported organisation leading fusion
Saurav Jha
Author and commentator on energy and security, based in New Delhi
research in India is the Institute of Plasma Research (IPR). with its main campus in Gandhinagar. India’s indigenously developed tokamaks are all sited on the main IPR campus. (A unit imported from Japan is at the Variable Energy Cyclotron Center, Kolkata.) IPR’s leading light was the late Predhiman K Kaw, who drove this fledgling organisation to leapfrog directly to contemporary tokamak technology, instead of pursuing what turned out to be less- promising approaches to confining a hot and dense plasma (which is at the core of fusion) in the conditions necessary for thermonuclear fusion to take place. Under Kaw’s leadership, IPR, which had initially started
off as a small effort under India’s Department of Science & Technology, managed to become a full-blown institute. It commissioned India’s first tokamak called the Aditya in 1989. Aditya’s first ‘shot’ was conducted in the same year.
Aditya and SST-1 Aditya was set up as a tokamak with copper coils with a major radius of 0.75m and minor radius of 0.25m. It was designed to generate a circular plasma and operate with a toroidal field of 0.75-1 tesla (T), a maximum plasma current of 250kA and a pulse duration of up to 250 milliseconds. Its heating and current drive is provided by a combination of ion cyclotron resonance heating (ICRH), electron cyclotron resonance heating (ECRH) and lower hybrid current drive (LHCD).
Besides becoming a mothership for developing the
relevant human resources within the country, Aditya has also yielded rich scientific dividends for IPR. Some very
54 | February 2022 |
www.neimagazine.com
important results on turbulent processes in tokamaks, which are of considerable interest to the global tokamak effort have been obtained through its use. Aditya was the first to establish that transport plasma
was not a steady ooze but was instead ‘bursty’. Experiments conducted using Aditya have also yielded important ways and means to mitigate plasma instability issues such as magnetohydrodynamics-generated disruptions and runaways. As an aside, disruptions lead to the rapid loss of the
plasma’s stored thermal and magnetic energy, which in turn necessitates the introduction of mitigation systems that shield plasma-facing components (PFCs) from the heat flux and forces thus created. A disruption can also lead to generation of very high energy electrons or ‘runaways’, which in turn can cause the first wall (ie PFCs) of the tokamak to melt, followed by leaks in water cooling circuits. To ensure that Aditya kept ‘giving’, it was decided to
upgrade it to a divertor configuration with a view to carrying out experiments with shaped plasmas relevant to contemporary tokamak designs. The philosophy behind this move was that small and medium-sized tokamaks are a convenient tool for testing new concepts, technologies and materials, which cannot be conducted on larger machines without preliminary studies, given the risks involved. However, there are actually very few small and medium-
sized tokamaks operational that have the advanced features required for providing experimental support relevant to large, advanced tokamaks. So Aditya-U (literally Aditya- Upgrade) was born, whose assembly from the disassembled Aditya was completed by December 2016 with operations beginning in January 2017. In comparison to its old form, Aditya-U has a circular
X-section vacuum vessel and buckling cylinder, safety and poloidal ring limiter, toroidal belt limiter, besides three sets of divertor coils. The modification to divertor configuration was achieved
by replacing the square cross-section vacuum vessel with the circular X-section type, creating space for the divertor coils. It has been designed to reach high temperatures (45keV or about half a billion degrees) and demonstrate good power exhaust efficiency. Aditya-U has already delivered a result that is
significant for ITER. An electro-magnetic pellet injection system that fires Li2
TiO3 pellets has been successfully
demonstrated as a viable method for disruption control. Significant suppression of runaway electrons has also been demonstrated in Aditya-U, through the use of periodic gas puffs that suppress edge density and potential fluctuations in the plasma.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61
