Instantaneous and efficient surface wave excitation of a low pressure gas or gases

A fluorescent lamp illumination system for substantially instantaneously providing partial ionization of a low pressure fill of gas or mixture of gases in a tube and subsequent continuous excitation of said low pressure gas or gases in a surface wave mode for emitting light along the length of the tube, comprising:

• a source of rf energy;
• a fill of a permanent, particular volume of low pressure inert gas or gases and mercury vapor;
• an elongated cylindrical tubular discharge container for confining said fill therein and having first and second closed ends and a cylindrical wall that is optically transparent to visible radiation, said wall having an inner surface and an outer surface, said container being permanently sealed to contain said fill, the inner surface of said discharge container being coated with phosphor said fill being in direct contact with said phosphor;
• coupling means having a predetermined impedance and responsive to rf energy from said rf source to couple the energy to said fill to both ionize at least a portion of said fill to create a weakly ionized plasma and to deliver the rf energy in a surface wave mode to energize the fill to sustain the plasma, a majority of the energy being delivered through said wall to an area near said inner surface to thereby instantaneously ionize and substantially continuously excite said fill so that the majority of mercury atoms of the mercury vapor near said inner surface produce u.v. photons that interact with the phosphor to produce visible light, said container having said first closed end mounted within said coupling means with the remainder of said container extending from said coupling means, said closed second end being remote and external to said coupling means, said rf energy being delivered solely and only to said first end of said container, said rf energy being well-defined surface waves;
• rf energy transmitting means having a predetermined impedance for transmitting rf energy from said source to said coupling means;
• and
• an rf shield around said container;
• said coupling means having a predetermined impedance such that the total impedance of the combination of said coupling means, said rf shield, and said discharge container, when said fill is continuously ionized and excited, is matched to said predetermined impedance of said rf energy transmitting means, said predetermined coupling means impedance being partially matched to said rf energy transmitting means impedance when said fill is un-ionized, said partial matching being sufficient to instantly weakly ionize said fill upon application of rf energy from said source to said coupling means.