HTPAC or high tolerance plasma arc cutting, also known as fine plasma, high definition plasma and plasma constricted arc, is a further development of plasma arc technology. The process is designed to improve the precision of plasma cutting for materials under 12mm thickness and offers a low cost alternative to laser cutting. A number of proprietary systems have been developed, all of which are designed to constrict the arc to a smaller diameter than conventional plasma arc cutting. The techniques used include improved gas flow control by nozzle design and magnetic field confinement. The constriction of the plasma arc results in increased energy density, and improvements in cutting speed and edge squareness.