Method and apparatus for increasing channel plasma density in an MHD vacuum pump

• Main Authors: JAHNS; GARY L, ENSBERG; EARL S
• Format: Patent
• Language: English
• Published: 02.11.1999
• Edition: 6
• Subjects: CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; DYNAMO-ELECTRIC MACHINES; ELECTRICITY; GENERATION

Flat, insulated, metallic strips ("applicators"), are fixed to the wider sides of each permanent magnet assembly in the channel array of a Magnetohydrodynamic (MHD) Vacuum Pump. Electromagnetic power from an external rf/microwave generator is delivered by an appropriate transmission line to each pair of applicators, providing an rf/microwave electric field, generally parallel to the magnetic field of the magnets, across each channel in the array. As the plasma ions and electrons formed by the rf/microwave field lose energy by collisions with the channel surfaces and by collisions with neutral molecules in the channel, the microwave electric field reheats the plasma throughout its passage through the length of the channel array, increasing plasma density and enabling the use of much longer channels, thus increasing the throughput and compression ratio in the MHD Vacuum Pump.