Helical coupler for use in an electrodeless light source

A light source including:

• a. a source of power at a high frequency,
• b. an electrodeless lamp having an envelope made of a light transmitting substance and a volatile fill material capable of emitting light upon excitation enclosed within the envelope, and
• c. a termination fixture coupled to the source, the fixture including an inner conductor and an outer conductor disposed around the inner conductor, the conductors having lengths of a quarter wavelength and cross-sectional dimensions selected to produce a fixture characteristic impedance which matches the real portion of the lamp impedance in the excited state to the impedance of the coupled source, and
• d. the fixture further including a reactive impedance device coupled between the end of the inner conductor and the lamp, the device being selected to cancel a portion of the reactive part of the complex impedance of the lamp in the excited state, thereby enhancing the impedance match between the lamp and the source.