PhD and MPhil Thesis Classes - Université Libre de Bruxelles

1.6 Power Balance and Lawson CriteriaIn radio-frequency heating, high-frequency waves are generated by oscillators outsidethe torus. If the waves have a particular frequency (or wavelength), their energycan be transferred to the charged particles in the plasma in the same way that microwavestransfer heat to food in a microwave oven. These heated charged particles inturn collide with other plasma particles, thus increasing the temperature of the bulkplasma.Figure 1.4: Schematic representation of heating methods for plasma. The figure is takenfrom JET website: http://www.jet.efda.org.1.6 Power Balance and Lawson CriteriaFusion confinement requirements are qualified in terms of energy and particle confinementtimes. The energy confinement time, τ E , is defined in terms of a steady stateplasma asτ E ≡ U W in(1.5)where U is the measured plasma energy content and W in is the rate of the energy inputnecessary to sustain the steady state.The particle confinement time, τ p , is defined analogously in terms of particle contentand replacement rate.7