NOVELTY - The source has a connection terminal operably coupled to an energy shaping unit for accepting an electrical stimulus from an ignition control system associated with a combustion engine. The electrical stimulus triggers a sustained radio frequency (RF) oscillation between the energy shaping unit and a tapered quarter wave coaxial cavity resonator (QWCCR) such that an RF corona is formed near a center conductor (704) of the QWCCR to ionize a portion of combustible material i.e. petrol vapor, in the combustion chamber for causing ignition of the combustible material.    USE - Ignition source i.e. quarter wave coaxial cavity igniter, for igniting a combustible material i.e. petrol vapor, in a combustion chamber of a combustion engine i.e. internal combustion engine, of an automobile.    ADVANTAGE - The QWCCR is made of low loss materials, so that quality factor and associated resonant field step-up to higher potentials of the QWCCR are improved. The QWCCR ensures that dynamic impedance matching and/or frequency tracking functions are implemented in power and control systems, thus improving energy delivery to a corona discharge plasma after breakdown and increasing energy delivery to the QWCCR. The QWCCR delivers specific amount of energy to the source in short and controlled period of time, so that operation at high power levels of the engine is achieved. The source is easily adapted to the combustion engine without modifying the design of the engine and an ignition control system.    DETAILED DESCRIPTION - The energy shaping unit is selected from a group consisting of a negative resistance device incorporated into the QWCCR, an RF field effect transistor, spark gap, a pulse amplifying device, an electron tube, an electron drift tube, a traveling wave tube, an amplitron and a magnetron. INDEPENDENT CLAIMS are also included for the followings:    (1) a plasma ignition system comprising a waveform generator    (2) a method for igniting a combustible material in a combustion chamber of a combustion engine.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of a tapered quarter wave coaxial cavity resonator in which a power shaping unit comprises a spark gap near a base of a center conductor of the coaxial cavity resonator.    Corona discharge plasma (210)    Insulated guide (510)    Electrical return path (514)    Base of center conductor (516)    Center conductor (704)