Why fusion needs very high temperatureसंलयन के लिए बहुत उच्च ताप क्यों चाहिएWhy fusion needs very high temperature

NCERT Section 13.7.2 · Class 12 Physics · Chapter 13 · interactive diagram

Parts and what they mean

• Coulomb barrier (कूलॉम अवरोध) — Both nuclei are positive, so they repel. Potential energy = k(e)(e)/r rises as they come closer.
• Barrier height ≈ 400 keV (अवरोध की ऊँचाई ≈ 400 keV) — For two protons the barrier is about 400 keV (NCERT). It is higher for nuclei with more charge.
• Short-range nuclear attraction (लघु-परासी नाभिकीय आकर्षण) — Once the nuclei touch, the strong attractive nuclear force takes over and they can fuse.
• Typical thermal energy in the Sun (सूर्य में सामान्य तापीय ऊर्जा) — (3/2)kT at 1.5 × 10⁷ K ≈ 2 keV — far below 400 keV. Only the rare, much faster protons fuse (to reach 400 keV on average needs T ≈ 3 × 10⁹ K).

Original diagram drawn by Simple Learning Hub, based on NCERT Section 13.7.2. Report a mistake