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5 Jul 1999

Volume 75, Issue 1, pp. 1-147

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Radio frequency plasma processing effects on the emission characteristics of a MeV electron beam cathode

J. I. Rintamaki, R. M. Gilgenbach, W. E. Cohen, R. L. Jaynes, M. E. Cuneo, and P. R. Menge

Appl. Phys. Lett. 75, 31 (1999); http://dx.doi.org/10.1063/1.124267 (3 pages) | Cited 6 times

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Experiments have proven that surface contaminants on the cathode of an electron beam diode influence electron emission current and impedance collapse. This letter reports on an investigation to reduce parasitic cathode current loss and to increase high voltage hold off capabilities by reactive sputter cleaning of contaminants. Experiments have characterized effective radio frequency (rf) plasma processing protocols for high voltage anode–cathode (A–K) gaps using a two-stage argon/oxygen and argon rf plasma discharge. Time-resolved optical emission spectroscopy measures contaminant (hydrogen) and bulk cathode (aluminum) plasma emission versus transported axial electron beam current turn on. Experiments were performed at accelerator parameters: V = −0.7 to −1.1 MV, I(diode)=3–30 kA, and pulse length=0.4–1.0 μs. Experiments using a two-stage low power (100 W) argon/oxygen rf discharge followed by a higher power (200 W) pure argon rf discharge yielded an increase in cathode turn-on voltage required for axial current emission from 662±174 kV to 981±97 kV. The turn-on time of axial current was increased from 100±22 to 175±42 ns. © 1999 American Institute of Physics.
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79.70.+q Field emission, ionization, evaporation, and desorption
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition

Secondary electron energy spectra emitted from radio frequency biased plasma electrodes

D. M. Shaw, M. Watanabe, H. Uchiyama, and G. J. Collins

Appl. Phys. Lett. 75, 34 (1999); http://dx.doi.org/10.1063/1.124268 (3 pages) | Cited 10 times

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The ion-induced secondary electron energy spectra from a radio frequency biased (13.56 MHz) electrically insulating (Al2O3) plasma electrode surface immersed in a separately powered inductively coupled plasma are studied both experimentally and theoretically. Radio frequency (rf) electrode bias voltages of 140 and 285 V (peak to ground) are employed and the complete electron energy spectra emitted from the electrode and accelerated by the rf sheath are measured 14 cm from the rf biased electrode using a differentially pumped retarding potential analyzer. A collisionless radio frequency Child–Langmuir sheath model is used to explain the experimentally measured electron energy spectra. © 1999 American Institute of Physics.
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79.20.Hx Electron impact: secondary emission

Modulated rf discharges as an effective tool for selecting excited species

Grazia Cicala, Mariadriana Creatore, Pietro Favia, Ritalba Lamendola, and Riccardo d’Agostino

Appl. Phys. Lett. 75, 37 (1999); http://dx.doi.org/10.1063/1.124269 (3 pages) | Cited 18 times

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Modulated NH3-fed rf glow discharges have been investigated; the emissions of the active species NH∗ and N2∗ have been collected during the modulation period (time on+time off). In this study, modulated discharges have been characterized by a constant time on of 7 ms and a tunable time off in the range of 0–1000 ms. It has been found that the power modulation represents an effective tool for selecting excited species: this procedure may be exploited in surface grafting treatments of polymers where high selectivity of chemical groups is requested, e.g., for preferentially grafting −NH2 groups onto polyethylene with respect to all other N-containing functionalities. © 1999 American Institute of Physics.
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52.80.Pi High-frequency and RF discharges
52.80.Hc Glow; corona
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.65.-b Surface treatments
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
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