How do radiation, conduction, and convection cause energy losses in fusion plasma?

In fusion plasma, energy losses must be managed to maintain the high temperatures required for ignition. These losses occur through several physical mechanisms:1

• Radiation: As electrons scatter from positively charged ions, they accelerate and emit energy in the form of electromagnetic radiation, a process known as bremsstrahlung. This loss is proportional to the square of the ion density and the square root of the plasma temperature.1
• Conduction and Convection: Heat escapes the plasma core through the transport of energy across magnetic field lines, often driven by particle collisions and plasma turbulence. While classical diffusion theory predicts certain loss rates, experimental observations often show energy escaping at 10 to 100 times the expected rate due to anomalous transport. These processes, along with other heat-loss mechanisms, are characterized by an energy-loss time constant ($\tau$), which represents the duration the plasma can retain its heat.21

To achieve practical fusion, the energy released by fusion reactions must be sufficient to compensate for these combined losses, maintaining the plasma's temperature against the cooling effects of radiation, conduction, and convection.1