Definition
A semiconductor diode designed to conduct heavily in the reverse direction once the voltage across it reaches a specific breakdown value, without being damaged. At that breakdown point, the electric field inside the diode accelerates electrons hard enough to knock additional electrons free, which in turn knock more free, producing a rapid cascade of current flow. Avalanche diodes are used to protect circuits from voltage spikes and to hold a steady reference voltage.
Plain English
An electronic part that normally blocks current going the wrong way, but is built to safely let a sudden burst of current through if the voltage gets too high. It acts like a pressure-release valve for electricity.
Context Anchor
Seen in aircraft electrical and electronic circuit discussions, especially in voltage regulation, surge protection, and component-level maintenance.
Derivation
From the French 'avalanche', meaning a sudden rush of snow down a mountain. The name fits the way one freed electron triggers another, which triggers more, multiplying quickly into a rush of current.
Why Pilots Care
It prevents damaging voltage spikes from reaching avionics and flight instruments, keeping electrical systems stable throughout the flight.
Analogy
Think of it like a pressure relief valve in a plumbing system. It stays closed during normal conditions, but opens at a set pressure to keep the system from being damaged.
Intuition Check
Do not read “avalanche” as meaning accidental destruction. In an avalanche diode, the avalanche action is intentional and controlled when the part is used within its limits.
Example Sentence 1
The voltage regulator uses an avalanche diode to keep the output steady even when the alternator load changes.
Example Sentence 2
During the electrical system check, the avalanche diode clamped the test voltage at its rated level without allowing further rise.