India has taken a major step forward in its nuclear fusion ambitions with a key technological breakthrough at the Institute for Plasma Research (IPR) in Gandhinagar, Gujarat. Engineers have successfully commissioned and integrated an advanced 82.6 GHz, 400-kilowatt Gyrotron system into the nation’s flagship Steady State Superconducting Tokamak-1 (SST-1).
This upgrade significantly boosts India’s capacity to heat and maintain ultra-hot plasma at temperatures surpassing 100 million degrees Celsius, reaching the extreme thermal conditions required to force hydrogen atomic nuclei to fuse.
Nuclear fusion is often colloquially called an "artificial sun" because it aims to replicate the fundamental process powering the stars, offering a path to virtually limitless, safe, and zero-carbon energy. India has strategically positioned itself as a critical global player in this field through both its domestic experimental facilities and its vital participation in international megaprojects.
The new 82.6 GHz system serves as a high-power microwave generator, operating as an industrial-scale super-heater for atomic particles to tackle one of fusion's hardest obstacles: heating fuel particles efficiently. The system delivers up to 400 kilowatts of radio-frequency power through a custom 20-metre transmission line straight into the SST-1 tokamak core.
By utilising Electron Cyclotron Resonance Heating (ECRH), the system directs microwave energy precisely at electrons inside the magnetic field, transferring kinetic energy to raise plasma temperatures rapidly. Unlike its 42 GHz predecessor, the new 82.6 GHz gyrotron can operate at both fundamental and second-harmonic wave frequencies.
This flexibility enables Indian scientists to achieve breakdown pre-ionisation at higher magnetic fields of around 2.8 Tesla while sustaining stable plasma profiles over extended operational durations.
India’s primary experimental tokamak, SST-1, operates in tandem with ADITYA-U, a medium-sized conventional air-core tokamak designed to test plasma diagnostic tools, impurity control strategies, and magnetic pulse scenarios.
Together, these machines form the experimental core of India’s Department of Atomic Energy (DAE), serving as training grounds for plasma physicists and testing platforms for hardware before scaling up to power-producing reactors.
Inside the actual Sun, gravitational pressure compresses hydrogen atoms at temperatures of roughly 15 million degrees Celsius, forcing protons to overcome electrostatic repulsion and fuse into helium while releasing massive energy. Because Earth lacks a star’s immense gravitational mass, terrestrial reactors must compensate by reaching far higher temperatures, typically between 100 million and 200 million degrees Celsius.
At these extreme temperatures, matter enters a plasma state made of free-roaming positive ions and negative electrons. Since no physical vessel on Earth can touch a 100-million-degree plasma without instantly vaporising and cooling the reaction, scientists use a doughnut-shaped vacuum chamber wrapped in powerful electromagnets, known as a tokamak, which was originally invented by Soviet physicists in the 1950s.
Inside a tokamak, superconducting magnetic coils generate toroidal and poloidal magnetic fields. This combined magnetic field traps charged plasma particles, forcing them to spirally orbit invisible field lines without touching the metal vessel walls.
Because standard Ohmic heating from electrical currents loses effectiveness as plasma resistance drops at high temperatures, reactors rely on auxiliary heating like Neutral Beam Injection (NBI), Lower Hybrid Current Drive (LHCD), and Electron or Ion Cyclotron Resonance Heating via gyrotrons.
Most fusion reactors run on two heavy isotopes of hydrogen: Deuterium, which is easily extracted from ocean water, and Tritium, which can be bred inside reactor walls using lithium. The resulting fusion reaction yields high-energy alpha particles and fast neutrons, carrying kinetic energy that can ultimately be converted into steam to drive electricity turbines.
India’s journey into nuclear fusion started in the late 1980s with the construction of ADITYA, its first indigenously designed tokamak. By the late 1990s, the Institute for Plasma Research conceptualised SST-1 to join an elite group of international research facilities exploring steady-state superconducting technology.
Located in Gandhinagar, SST-1 has a major radius of 1.1 metres and a minor radius of 0.2 metres, featuring a magnet system that made it one of the first medium-sized tokamaks to use superconducting toroidal field coils cooled by two-phase liquid helium.
Indian industrial partners, including Godrej & Boyce, played a central role in fabricating these complex superconducting coils. SST-1 is designed as a long-pulse research platform aimed at sustaining plasma discharges for up to 1,000 seconds, studying plasma-wall interactions, and refining radio-frequency current drive mechanisms.
Meanwhile, its upgraded counterpart ADITYA-U operates with a major radius of 0.75 metres, serving as a nimble testbed for fundamental plasma physics, edge-plasma turbulence, disruption prediction, and diagnostic sensor validation.
Building on SST-1 data and engineering experience from international projects, India is preparing for its next major leap with SST-2. Conceptualised as a prototype demonstration reactor (DEMO-class facility), SST-2 is envisioned as a reactor-scale device with advanced plasma shaping, higher magnetic fields, and a tritium-breeding test blanket module.
Alongside state-funded infrastructure, India's deep-tech start-up ecosystem is entering the fusion space. Start-Ups like PranosFusion are exploring compact tokamak configurations, such as their 'Pragya' prototype, signalling a broader shift toward public-private collaborations similar to trends in the United States and Europe.
While domestic research facilities provide valuable hands-on experience, India’s primary strategic vector in fusion energy remains its full partnership in ITER (International Thermonuclear Experimental Reactor). Located in Cadarache in southern France, ITER is a massive ₹2,18,000 crore megaproject built by a coalition of seven primary partners: India, China, the European Union, Japan, South Korea, Russia, and the United States.
As an equal partner, India is responsible for delivering 9 per cent of ITER’s physical, in-kind hardware contributions along with financial and scientific backing. Managed by the ITER-India division within IPR, Indian industry has manufactured and delivered critical core components for the project.
The single largest component delivered to ITER is its cryostat, a massive stainless steel pressure chamber measuring nearly 30 metres in height and diameter, weighing over 3,850 tons. Fabricated by Indian engineering giant Larsen & Toubro (L&T) at its Hazira facility in Gujarat, the cryostat encapsulates the entire tokamak and its superconducting magnets, insulating them at near absolute zero (-269°C). The precision required to assemble these thousand-ton segments to sub-millimetre tolerances demonstrated India's high-end manufacturing capabilities.
India has also delivered over 900 custom-designed In-Wall Shielding (IWS) neutron-absorbing block assemblies installed inside the double-walled vacuum vessel to protect outer magnets from high-energy neutrons.
Additionally, Indian engineers supplied the heat rejection cooling water system to clear hundreds of megawatts of thermal energy, along with high-power Ion Cyclotron RF heating sources, Diagnostic Neutral Beam lines, and megawatt-scale high-voltage power conversion systems.
In return for its 9 per cent in-kind hardware delivery, India gains 100 per cent access to all intellectual property, operational data, and technological breakthroughs generated by ITER.
When comparing India's progress to other global fusion efforts, China's EAST (Experimental Advanced Superconducting Tokamak) in Hefei is frequently cited as a frontrunner in long-pulse magnetic fusion. EAST is significantly larger than SST-1, featuring a major radius of 1.85 metres and operating with fully superconducting toroidal and poloidal niobium-titanium magnet coils that allow flexible plasma shaping.
EAST holds remarkable performance records, including maintaining a continuous high-confinement steady-state plasma pulse for 1,056 seconds (over 17 minutes). It has also sustained electron temperatures exceeding 120 million degrees Celsius for over 100 seconds, peaking at 160 million degrees Celsius for shorter runs.
By contrast, India’s SST-1 has focused on overcoming initial magnet commissioning challenges and liquid helium cooling protocols, maintaining pulse durations in shorter multi-second to sub-minute bursts as heating tools like the new gyrotron are integrated.
China’s national roadmap is focused on aggressive deployment, constructing the HL-3 tokamak in Chengdu and developing CFETR (China Fusion Engineering Test Reactor), a next-generation device aimed at generating up to 1 gigawatt of fusion power in the 2030s.
India's roadmap uses a two-pronged strategy: leveraging ITER to acquire large-scale reactor technology while steadily building domestic self-reliance through SST-1, ADITYA-U, and SST-2.
Other global actors hold significant milestones as well. South Korea’s KSTAR facility holds the world record for sustaining plasma ion temperatures at 100 million degrees Celsius for 48 seconds, assisted by an advanced tungsten divertor. KSTAR aims to reach 300 seconds of 100-million-degree operation in the near future.
In late 2023, Japan and the European Union inaugurated JT-60SA in Naka, Japan, which currently stands as the world's largest operational superconducting tokamak prior to ITER, featuring a plasma volume of 135 cubic metres. In the United Kingdom, the historical JET facility achieved a record 69 megajoules of fusion energy during a 5-second pulse using a true deuterium-tritium fuel mix before concluding its experimental operations.
The United States pursues both magnetic and inertial confinement options alongside private venture capital. At the Lawrence Livermore National Laboratory, the National Ignition Facility (NIF) uses Inertial Confinement Fusion, focusing 192 ultra-powerful lasers onto a tiny fuel capsule.
NIF made history by achieving "scientific breakeven" ($Q > 1$), releasing more energy than the laser delivered and reaching energy gain ratios above 4. Meanwhile, private start-ups like Commonwealth Fusion Systems are building SPARC, a compact tokamak using High-Temperature Superconducting magnets to generate powerful magnetic fields in a smaller footprint.
Despite global progress, transitioning artificial sun experiments into commercial power plants presents major engineering obstacles. Reactor inner walls and divertors must withstand extreme heat loads of 10 to 20 megawatts per square metre, while 14-MeV neutrons degrade metals over time. Developing advanced tungsten alloys, liquid-metal divertors, and low-activation steels remains critical.
Plasma is also inherently prone to edge instabilities and sudden thermal disruptions that can damage walls within milliseconds, requiring real-time magnetic feedback systems and AI monitoring. Furthermore, because global supplies of natural Tritium are under 30 kilogrammes, reactors must successfully breed their own fuel using lithium interior blankets—a technology India and its partners plan to test extensively through ITER's Test Blanket Modules.
Finally, commercial power plants must progress past scientific breakeven ($Q = 1$) to achieve high net engineering power gains ($Q > 10 \text{ to } 22$) while accounting for total plant energy consumption.
Agencies
