Electrodeless light source having a lamp holding fixture which has a separate characteristic impedance for the lamp starting and operating mode

摘要

A lamp holding fixture for exciting an electrodeless lamp by high frequency power has a switchable characteristic impedance for impedance matching the lamp to the power source during both the starting and operating modes. The fixture has an inner conductor and two outer conductors of different dimensions in cross section. During the starting mode the inner conductor and the larger diameter outer conductor form the power coupling conductors for the fixture thereby providing a high characteristic impedance for matching the lamp impedance to the source output impedance. After starting, the smaller diameter outer conductor may be moved along its longitudinal axis until it contacts the power coupling end of the larger diameter outer conductor so that the inner conductor and the smaller diameter outer conductors form the power coupling conductors during the operating mode.