Arc initiation in cathodic arc plasma sources

Patent · Tue Jan 01 00:00:00 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 (United States)
• 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

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