Method for igniting a thermal turbomachine

A method for igniting fuel in a combustion chamber of a thermal turbomachine, comprising:

• a combustion chamber, an ignition device, a fuel supply and an air supply, the ignition device including an ignition space and of an ignitor arranged in the ignition space, the fuel supply and the air supply discharging into the ignition space, and the ignition space being connected to the combustion chamber via a flame tube, wherein, prior to the ignition of the combustion chamber, an overall fuel/air mixture ratio Φoverall=1/λoverall greater than 1 is set in the flame tube, with λoverall being the overall air ratio, the fuel/air mixture is ignited by means of the ignitor in the ignition space, and the flame and the remaining fuel/air mixture runs from the ignition space through the flame tube to the combustion chamber and ignites the combustion chamber there, wherein the ignition operation is carried out by means of the ignitor in the ignition space with a lean fuel/air mixture.