Arc initiation in cathodic arc plasma sources

Patent · Tue Jan 01 04:00:00 EST 2002

OSTI ID:874809

Anders, Andre ^[1]

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1. Albany, CA

A "triggerless" arc initiation method and apparatus is based on simply switching the arc supply voltage to the electrodes (anode and cathode). Neither a mechanical trigger electrode nor a high voltage flashover from a trigger electrode is required. A conducting path between the anode and cathode is provided, which allows a hot spot to form at a location where the path connects to the cathode. While the conductive path is eroded by the cathode spot action, plasma deposition ensures the ongoing repair of the conducting path. Arc initiation is achieved by simply applying the relatively low voltage of the arc power supply, e.g. 500 V-1 kV, with the insulator between the anode and cathode coated with a conducting layer and the current at the layer-cathode interface concentrated at one or a few contact points. The local power density at these contact points is sufficient for plasma production and thus arc initiation. A conductive surface layer, such as graphite or the material being deposited, is formed on the surface of the insulator which separates the cathode from the anode. The mechanism of plasma production (and arc initiation) is based on explosive destruction of the layer-cathode interface caused by joule heating. The current flow between the thin insulator coating and cathode occurs at only a few contact points so the current density is high.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA
• DOE Contract Number: AC03-76SF00098
• Assignee: The Regents of the University of California (Oakland, CA)
• Patent Number(s): US 6465793
• OSTI ID: 874809
• Country of Publication: United States
• Language: English

Related Subjects

/250/
500
achieved
action
allows
anode
apparatus
applying
based
cathode
cathodic
caused
coated
coating
concentrated
conducting
conductive
connects
contact
current
current flow
density
deposited
deposition
destruction
electrode
electrodes
ensures
eroded
explosive
flashover
flow
form
formed
graphite
heating
hot
initiation
insulator
interface
joule
joule heating
kv
layer
layer-cathode
local
location
material
mechanical
mechanism
method
neither
nor
occurs
ongoing
path
plasma
power
power density
power supply
production
provided
repair
required
separates
simply
sources
spot
sufficient
supply
supply voltage
surface
surface layer
switching
trigger
triggerless
v-1
voltage