Basics About Tokamak
- A tokamak is a device designed to harness nuclear fusion, the reaction that powers the sun and all the stars.
- In a tokamak, magnetic field coils confine plasma to achieve the required conditions for fusion on the Earth.
- The first tokamak, T-1 began operation in Russia in 1958 and the subsequent advances led to the construction of the Tokamak Fusion Test Reactor at Princeton Plasma Physics Laboratory and the Joint European Torus in England.
- The tokamak enables fusion by creating an extremely hot plasma and confining it tightly using magnetic fields.
Principles of Tokamak
- Plasma
- The starting point is gas, which gets ionized into plasma, comprising freely moving electrons and ions.
- This plasma flow is channeled into a toroidal chamber.
- Magnetic Fields
- Powerful magnets create two main magnetic fields: a toroidal field going around the torus and a poloidal field crossing it.
- This creates a helical field to contain the plasma.
- Confinement
- The charged particles spiral along the magnetic field lines without hitting the walls, as fields exert radial inward forces to balance the outward plasma pressure.
- This traps the plasma in a stable vortex.
- Current Drive
- Electric currents flowing in the plasma strengthen the confining magnetic fields.
- External systems drive and sustain these tokamak currents.
- Heating Systems
- Various electromagnetic waves and particle beams are aimed at the plasma to heat it to over 150 million °C for fusion reactions.
- Fusion
- Hydrogen isotopes undergo fusion at such extreme temperatures, releasing energy.
Advantages of Tokamak
- Abundant fuel source.
- No GHG emissions.
- Minimal radioactive waste.
Initiatives by India
- ADITYA-U:
- ADITYA Upgrade (ADITYA-U) is an upgraded version of ADITYA tokamak, which operated since 1989. It is a medium-sized tokamak with a maximum toroidal magnetic field of 1.5 T.
- It has been designed to produce circular plasmas with a current of nearly 150–250 kA and a plasma duration of around 250–350 milliseconds.