How Xenon Strobes Work

Xenon strobes work by discharging the energy stored in a capacitor through a special flash tube filled with xenon gas at a low pressure to produce a very short burst of high intensity white light.

It produces it flash in 5 steps:

  1. The energy storage capacitor connected across the flash tube is charged from the power supply to a voltage around 300vdc.
  2. Normally, the flash tube remains non-conductive even when the capacitor is fully charged and therefore does not flash.
  3. A separate small capacitor (e.g. 100 nF) is charged from the same power supply to generate a trigger pulse.
  4. The pulse generated by this trigger (typically 5 to 10 kV) is enough to ionize the xenon gas inside the flash tube.
  5. The ionized xenon gas suddenly becomes a low resistance and allows the energy stored on the capacitor to discharge through the flash tube resulting in a short duration brilliant white light.

A typical flash duration is from a few milliseconds down to a fraction of a millisecond. For a typical xenon strobe beacon, the trigger circuit includes timing components to generate a repetitive pulse at say, once every second, such that the beacon produces a string of flashes 60 times a minute.

Strobes can flash at slower rates than this with no issues but there is a limit if they are required to flash faster – the typical maximum flash rate is 4 flashes per second plus it takes a finite amount of time to charge up the flash capacitor to its maximum voltage. Therefore, most xenon strobe beacons have a maximum flash rate of 2 or 3 flashes per second.

The flash tube on a xenon strobe beacon is made of hard glass or quartz glass with sealed-in electrodes at each end. Various shapes are available such as U or linear. Flashtubes are light sources with high power density so can only be made of high temperature materials. Most flash tubes are equipped with a capacitive trigger electrode (a wire wrapped around the tube or a silver conductive coating on the outside of the glass).

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