Honeycomblike large area LaB6 plasma source for Multi-Purpose Plasma facility

Abstract

A Multi-Purpose Plasma (MP(2)) facility has been renovated from Hanbit mirror device [Kwon et al., Nucl. Fusion 43, 686 (2003)] by adopting the same philosophy of diversified plasma simulator (DiPS) [Chung et al., Contrib. Plasma Phys. 46, 354 (2006)] by installing two plasma sources: LaB(6) (dc) and helicon (rf) plasma sources; and making three distinct simulators: divertor plasma simulator, space propulsion simulator, and astrophysics simulator. During the first renovation stage, a honeycomblike large area LaB(6) (HLA-LaB(6)) cathode was developed for the divertor plasma simulator to improve the resistance against the thermal shock fragility for large and high density plasma generation. A HLA-LaB(6) cathode is composed of the one inner cathode with 4 in. diameter and the six outer cathodes with 2 in. diameter along with separate graphite heaters. The first plasma is generated with Ar gas and its properties are measured by the electric probes with various discharge currents and magnetic field configurations. Plasma density at the middle of central cell reaches up to 2.6 x 10(12) cm(-3), while the electron temperature remains around 3-3.5 eV at the low discharge current of less than 45 A, and the magnetic field intensity of 870 G. Unique features of electric property of heaters, plasma density profiles, is explained comparing with those of single LaB(6) cathode with 4 in. diameter in DiPS.

New low temperature multidipole plasma device with a magnetic X-point and its properties

“…LaB 6 cathode. Based on a reported LaB 6 DC plasma source [51], we have developed a LaB 6 cathode system and installed it in MAXIMUS as shown in figure 7. The cathode system is designed such that the LaB 6 disk is placed on the axial center of the first chamber at z = 22 cm.…”

Note: Arc discharge plasma source with plane segmented LaB6 cathode

“…A "honeycomb cathode" with ∼22 cm diameter was developed at the MP 2 facility. 3 However, it was designed as a large diameter central disk surrounded by six disks of smaller diameter and did not have a close-packed emitting area. Although formally it is a large-area cathode, it is not evident if it would be capable of producing high-density homogeneous plasma stream.…”