Mains Answer Writing - 20 Jan, 2026
GS3
Science & Technology
10 marks
What is the Greenwald limit in nuclear fusion research? Why is China’s EAST fusion reactor achieving stable plasma density beyond this limit considered important?
Tips for your answer
- Define first, in one line: Begin by clearly explaining the Greenwald limit as the maximum safe plasma density in a tokamak beyond which plasma becomes unstable.
- Link to fusion feasibility: Briefly state why higher plasma density is crucial for fusion—more collisions, higher energy output, and progress towards sustained fusion.
- Highlight significance, not details: Focus on why EAST’s achievement matters (breaking a long-standing design barrier, improving prospects of viable fusion energy), without going into excessive technical depth.
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