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Category: electronics & instrumentation

BSA 00-03: Plasma Valve

BNL Reference Number: BSA 00-03

Patent Status: U.S. Patent Number 6,528,948 was issued on March 4, 2003

Summary

The invention describes a fast igniting plasma valve that can be used as an emergency valve in machine processes that require maintenance of vacuum. Unlike mechanical valves, plasma valves can be ignited faster and can close without causing damage to the machinery in which they are operating because the valves have no moving parts. The plasma valve has proven capability to separate between vacuum and atmosphere.

Description

Describes a plasma valve that contains a confinement channel and primary anode and cathode within. An ignition cathode is placed adjacent to the primary cathode. The power supplies are joined to the cathodes and anode for rapidly igniting and maintaining plasma in the channel. The plasma prevents leakage of atmospheric pressure through the channel. The valve's outer structure is comprised of a hollow, water-cooled copper cylinder located between three cathodes and a hollow anode ring at the opposite end of the cylinder. When activated, the plasma valve is composed of an ionized gas, or a gas with charged particles confined by electric and magnetic fields, that fills an airtight aperture. When the plasma reaches certain temperature and density parameters, it separates atmospheric pressure from a vacuum, which must be devoid of pressure. When a vacuum is breached, a plasma arc is ignited in less than one nanosecond inside the plasma valve. The plasma valve is about 50 times hotter than room temperature, this intense heat makes the ionized atoms and molecules move around and collide with air molecules so rapidly that the ions block any air molecules that might pass through the plasma valve.

Benefits

Unlike a mechanical valve the described plasma valve has no moving parts, does not require much maintenance, and establishes a vacuum-air separation much faster.

Applications and Industries

Fast acting valves in UHV beamlines. In case of vacuum breach, plasmas can be ignited faster than mechanical valves without damage to beamline (unlike,presently used, msec spring loaded shutters). The plasma windows can be used for non-vacuum electron beam welding, non-vacuum material modifications by ion implantation, and dry etching, or micro-fabrication and electron beam melting for manufacturing alloys.