PMC Capri Super sunlamp
GLOW-IGNITION
Glow ignition is a method that used a third electrode,
the start anode, positioned near the cathode. A
serial resistor R2 limited the current to such a level
that only a glow discharge between the cathode and
the additional start anode could develop. This glow
discharge caused the gas pressure and the
temperature in the tube to increase until a level
where an arc discharge between the cathode and
the main anode would be established. After the
ignition, the voltage at the supply end of R2 dropped
and the initial glow discharge reduced to a
minimum. Almost all high pressure mercury vapour
arc discharge tubes as applied in sunlamps were
ignited with an additional start anode or. For AC
operation even a second start anode could be used,
as with the PMC Capri Super sunlamp on display
here.
