About  

• These are also known as Mach diamonds. 
• These are alternating bright and dark patches in the exhaust plume of rockets or jets operating at supersonic speeds. 
• Formation: 
  • Supersonic Exhaust Release: Exhaust exits the engine at supersonic speeds, with pressure potentially lower than the atmospheric pressure at that altitude. 
• Compression and Expansion: 
  • The atmosphere compresses the exhaust until its pressure equals atmospheric pressure. 
  • Over-compression can cause the exhaust to expand outward, dropping its pressure. 
  • This seesawing process repeats, creating pressure waves in the exhaust plume. 
• Shock Wave Interaction: 
  • Atmospheric pressure forces the outward-diverging exhaust to bend inward. 
  • As the pressure rises, temperature increases, igniting residual fuel and forming bright spots (shock diamonds). 
  • Alternating inward and outward bending generates shock waves, creating the diamond pattern. 
• Characteristics: 
  • Appearance: Alternating bright and dark patches in the exhaust. 
  • Bright Spots: Result of fuel combustion in high-pressure regions. 
  • Dark Patches: Indicate areas of lower temperature and pressure. 
• Applications: 
  • Rocket and Jet Engines: Seen during high-thrust operations. 
  • Visual Indicator: Reflects the behavior of supersonic exhaust flows and pressure dynamics. 
  • Shock diamonds illustrate the complex interactions of pressure, temperature, and shock waves in supersonic exhaust plumes. 

Shock Diamonds at the Exhaust of Supersonic Jet.