ROD SEAL
The Rod seal, also known as the Hard seal, is by far the most common and cost effective high-performance lamp seal. The grading glass is specially formulated to allow for the thermal expansion between the tungsten rod of the electrode and the quartz envelope. The shape of the seal resembles a vaulted arch. The shape is important in that it is structurally sound against the high pressure shockwave that occurs during every discharge.
Use: Low to High Average Power; Low to Medium Peak Power; CW to Moderate Rise Time; Fluid or Air Cooled.
Pulse Duration: > 80 mSec
Service Temperature: < 400ºC average
Cost: Low
RIBBON SEAL
The ribbon seal lamp is made by encapsulating a thin molybdenum foil with quartz. The quartz is shrunk down around the foil and part of the electrode thereby eliminating any dead space. This lamp is very rugged though the peak and RMS current must be low, generally below 20 amps RMS. The main application of this lamp is in CW Krypton Arc Lamps. It is ideally suited for use in environments where excessive vibrations may be encountered.
Use: Medium Average Power; Low Peak Power; CW to Very Long Rise Time; Fluid or Air Cooled.
Pulse Duration: > 1 mSec
Service Temperature: < 400ºC
Cost: High
RE-ENTRANT SEAL
This is a more complicated high performance seal than the Rod Seal. It also has grading glass suitable for dynamic temperatures and pressures. However, the inverted vaulted arch shape will handle greater pressure shock waves than the Rod Seal and is therefor recommended for applications where high peak power and very short rise times are encountered.
Use: Low to High Average Power; Low to High Peak Power; Very Short Rise Time; Fluid or Air Cooled.
Pulse Duration: > 5 mSec
Service Temperature: < 400ºC average
Cost: High
END-CAP SEAL
This is a low performance seal which is soldered onto the quartz envelope. As such, it is a low cost seal. The main disadvantages of these type of seals is that the lamps they are used on tend to have a much shorter life and are not capable of high average power operation like the high performance lamps.
Use: Low Average Power; Low to High Peak Power; CW to Medium Rise Time; Fluid or Air Cooled.
Pulse Duration: > 5 mSec
Service Temperature: < 200ºC average
Cost: Low
Diagrams provided by VBI Technologies (some modified.)