Abstract: The header and tunnel of an external core, solenoidal electric field, fluorescent lamp are coated with a thin ultraviolet light-reflective layer; for example, aluminum or magnesium oxide. Radiative heat transfer from the lamp plasma to the magnetic core is thus reduced to permit high operating power levels and good lumen maintenance.

Abstract: An electrodeless fluorescent lamp adapted for economical substitution in place of an existing incandescent lamp comprises an ionizable medium contained within a phosphor coated globular envelope. A closed loop magnetic core transformer, contained within a reentrant cavity in the base of the envelope, induces a radio frequency electric field which ionizes the medium to stimulate production of visible light output from the phosphor. A tubular extension of the envelope traverses the cavity, linking the core with a column of ionizable medium, to form a "secondary winding" on the transformer. A base assembly, attached to the envelope, supports a lamp plug for receipt of input energy. A radio frequency power supply, contained within the base assembly, provides electric current to a primary winding on the core.