Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Electron or ion source
Patent
1980-11-10
1982-08-10
La Roche, Eugene R.
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Electron or ion source
250423R, 313230, H01J 2704
Patent
active
043440193
ABSTRACT:
An ion source of the Penning discharge type having a self-cleaning aperture is provided by a second dynode (24) with an exit aperture (12) in a position opposite a first dynode 10a, from which the ions are sputtered, two opposing cathodes (14, 16), each with an anode (18, 20) for accelerating electrons emitted from the cathodes into a cylindrical space defined by the first and second dynode. A support gas maintained in this space is ionized by the electrons. While the cathodes are supplied with a negative pulse to emit electrons, the first dynode is supplied with a negative pulse (e.g., -300 V) to attract atoms of the ionized gas (plasma). At the same time, the second dynode may also be supplied with a small voltage that is negative with respect to the plasma (e.g., -5 V) for tuning the position of the plasma miniscus for optimum extraction geometry. When the negative pulse to the first dynode is terminated, the second dynode is driven strongly negative (e.g., -600 V) thereby allowing heavy sputtering to take place for a short period to remove virtually all of the atoms deposited on the second dynode from material sputtered off the first dynode. An extractor (22) immediately outside the exit aperture of the second dynode is maintained at ground potential during this entire period of sputtering while the anode, dynode and cathode reference voltage is driven strongly positive (about +20 kV to +30 kV) so that ions accelerated through the aperture will be at ground potential. In that manner, material from the first dynode deposited on the second dynode will be sputtered, in time, to add to the ion beam. Atoms sputtered from the second dynode which do not become ionized and exit through the slit will be redeposited on the first dynode, and hence recycled for further ion beam generation during subsequent operating cycles.
REFERENCES:
patent: 2883580 (1959-04-01), Kilpatrick
patent: 3566185 (1971-02-01), Gavin
patent: 3955118 (1976-05-01), Flemming
patent: 4135094 (1979-01-01), Hull
Gavin, A Sputtering Type Penning Discharge for Metallic Ions, Nuclear Instruments and Methods, 64, (1968), pp. 73-76.
Gavin Basil F.
MacGill Robert A.
Thatcher Raymond K.
Besha Richard G.
Clouse Clifton E.
Gaither Roger S.
La Roche Eugene R.
The United States of America as represented by the United States
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