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(11) | EP 0 321 792 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Microwave resonant cavity |
| (57) A microwave resonant cavity (10) for a spectroscopic light source includes a housing
(12) having therein a chamber (26) formed by side walls (14,16) and a cylindrical
outer wall (18). The side walls having aligned openings (22,24) therethrough which
are on the longitudinal axis of the outer wall (18). A refractory tube (34) which
is adapted to contain a gaseous plasma extends through the aligned openings (22,24)
and across the chamber (26) in the housing. The portion of the side walls (14,16)
of the chamber (26) adjacent the openings (22,24) are closer together than the remaining
portions of the side walls (14,16) so that the chamber (26) has a first portion (30)
around the refractory tube (34) which is narrower than a second portion (32) of the
chamber around the first portion. A coupling loop is electrically coupled to a side
wall (16) of the chamber (26) within the second portion (32) of the chamber (26) and
is connected to a coaxial connector (67,70) which extends through the outer wall (18)
of the housing (12) to deliver microwave power to the chamber (26). This provides
a resonant cavity (10) in which the plasma formed in the refractory tube (34) is very
short for increased power and greater brightness of the plasma. This also provides
a resonant cavity which requires no tuning and is more stable. |