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Formation of large-volume plasmas in a microhollow cathode sustained discharge with a needle-plate second anode

A large-volume glow discharge is produced using a microhollow cathode sustained discharge (MCSD) with a needle-plate second anode in argon. The length and volume of the glow discharge are approximately 3 cm and 7 cm3, respectively, and the electron density is on the order of 1011 cm−3. The MCSD is also simulated using a two-dimensional self-consistent fluid model with a single plate as the second anode. Both the experimental and simulated results show that MCSD generation originates from cooperative formation that involves the microhollow cathode discharge and a discharge that arises from the second anode. The second anode plays an important role in MCSD generation. The electric field and the average electron energy clearly increase in the region near the second anode. The influence of the structure of the second anode on the MCSD characteristics is investigated. When the second anode has a needle-plate structure instead of a single plate structure, the sustaining voltage, breakdown, and annihilation current of the cathode for MCSD decrease substantially, a higher discharge current is obtained, and a more stable, uniform MCSD is produced. The results also show that both needle and plate contribute to glow discharge formation in the region near the second anode.