Model for designing planar magnetron cathodes

Technical Report · Fri May 30 04:00:00 EDT 1997

DOI:https://doi.org/10.2172/16554· OSTI ID:16554

Garcia, M ^[1]

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1. Lawrence Livermore National Laboratory

Planar magnetron cathodes have arching magnetic field lines which concentrate plasma density to enhance ion bombardment and sputtering. Typical parameters are: helium at 1 to 300 milli-torr, 200 to 2000 gauss at the cathode, 200 to 800 volts, and plasma density decreasing by up to ten times within 2 to 10 cm from the cathode. A 2D, quasineutral, fluid model yields formulas for the plasma density: n(x,y), current densities: j(x,y), j{sub e}(x,y), j{sub +}(x,y), the electric field: E{sub y}(y), and the voltage between the cathode surface and a distant plasma. An ion sheath develops between the cathode and the quasineutral flow. The thickness of this sheath depends on processes in the quasineutral flow. Experiments shows that T{sub e} (3 {yields} 8 eV) adjusts to ensure that {alpha}{sub 0}{tau} {approx} 2.5 in helium, for ionization rate {alpha}{sub 0} (10{sup 4} {yields} 10{sup 5} s{sup -1}), and electron transit time to the unmagnetized plasma {tau} (10 {yields} 100 {micro}s). Helium glow discharge cathode fall {alpha}{sub 0}{tau} is about 2.5, though this occurs at much higher voltage.

• Research Organization: Lawrence Livermore National Lab., Livermore, CA (US)
• Sponsoring Organization: USDOE Office of Defense Programs (DP) (US)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 16554
• Report Number(s): UCRL-ID-127644-Rev-1; ON: DE98052271; BR: YN0100000
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CATHODES
ELECTRIC FIELDS
ELECTRONS
GLOW DISCHARGES
HELIUM
IONIZATION
MAGNETIC FIELDS
MAGNETRONS
PLASMA
PLASMA DENSITY
SPUTTERING
THICKNESS