Electrodeless fluorescent lamp with optimized amalgam positioning

A method for manufacturing a solenoidal electric field (SEF) fluorescent discharge lamp, comprising the steps of:

• providing a light-transmissive envelope having an interior phosphor coating for emitting visible radiation when excited by ultraviolet radiation, said envelope having an apex portion, said envelope further having a re-entrant cavity formed therein for containing an excitation coil, said re-entrant cavity having an exhaust tube with an extension toward said apex portion of said envelope, said extension being situated perpendicular to said exhaust tube and said re-entrant cavity, said extension having a tip;
• inserting an amalgam into said exhaust tube and maintaining said amalgam substantially at said tip of said extension thereof;
• forming an indentation in said exhaust tube at a predetermined location between said re-entrant cavity and said tip of said extension of said exhaust tube;
• forming an evacuation hole in said exhaust tube between said indentation and said re-entrant cavity;
• and
• evacuating and filling said envelope through said exhaust tube.

A fluorescent discharge lamp, comprising:

• a light-transmissive envelope containing an ionizable, gaseous fill for sustaining an arc discharge when subjected to a radio frequency magnetic field and for emitting ultraviolet radiation as a result thereof, said envelope having an interior phosphor coating for emitting visible radiation when excited by said ultraviolet radiation, said envelope having an apex portion, said envelope further having a re-entrant cavity formed therein;
• an excitation coil contained within said re-entrant cavity for providing said radio frequency magnetic field when excited by a radio frequency power supply;
• an exhaust tube having an extension extending through said re-entrant cavity and toward said apex portion of said envelope, said exhaust extension having a tip;
• an indentation formed in said exhaust tube at a predetermined location between said re-entrant cavity and said tip of said extension of said exhaust tube;
• an amalgam situated within said exhaust tube and maintained in position substantially at said tip of said extension by said indentation.

A fluorescent discharge lamp, comprising:

• a light-transmissive envelope containing an ionizable, gaseous fill for sustaining an arc discharge when subjected to a radio frequency magnetic field and for emitting ultraviolet radiation as a result thereof, said envelope having an interior phosphor coating for emitting visible radiation when excited by said ultraviolet radiation, said envelope having an apex portion, said envelope further having a re-entrant cavity formed therein;
• an excitation coil contained within said re-entrant cavity for providing said radio frequency magnetic field when excited by a radio frequency power supply;
• an exhaust tube having an extension extending through said re-entrant cavity and toward said apex portion of said envelope, said extension being situated perpendicular to said exhaust tube and said re-entrant cavity, said extension having a tip;
• an indentation in said exhaust tube at a predetermined location between said re-entrant cavity and said tip of said extension of said exhaust tube;
• an amalgam situated within said exhaust tube and maintained in position substantially at said tip of said extension by said indentation.