The multi-wire chamber uses an array of wires at a positive dc voltage (anode)s, which run through a chamber with conductive walls held at a lower potential (cathode). The chamber is filled with gas, such as an argon/methane mix, so that any ionizing particle that passes through the tube will ionize surrounding gaseous atoms and produce ion pairs, consisting of positive ions and electrons. These are accelerated by the electric field across the chamber, preventing recombination; the electrons are accelerated to the anode, and the positive ions to the cathode. At the anode a phenomenon known as a Townsend avalanche occurs. This results in a measurable current flow for each original ionising event which is proportional to the ionisation energy deposited by the detected particle. By separately measuring the current pulses from each wire, the particle trajectory can be found. Adaptations of this basic design are the thin gap, resistive plate and drift chambers. The drift chamber can also be subdivided into ranges of specific use in the chamber designs known as time projection, microstrip gas, and those types of detectors that use silicon.