rf modulation of positive‐ion energies in low‐pressure discharges

1990 ◽  
Vol 68 (11) ◽  
pp. 5519-5527 ◽  
Author(s):  
S. G. Ingram ◽  
N. St. J. Braithwaite
Keyword(s):  
Low Pressure ◽  
Ion Energies ◽  
Positive Ion

Ammonia in the Ion-Source. III. Clustering With N-Oxides, Sulfoxides and Sulfones

1986 ◽  
Vol 39 (12) ◽  
pp. 2161 ◽  
Author(s):  
RG Gillis
Keyword(s):  
Chemical Ionization ◽  
Low Pressure ◽  
Ion Source ◽  
Unimolecular Decomposition ◽  
Positive Ion

Under positive ion chemical ionization conditions, with ammonia as reagent gas at relatively low pressure, N-oxides, sulfoxides and sulfones form clusters with a proton and one or more ammonia molecules; these clusters can be represented as [M+H]+, [M+NH4]+, [M+N2H7]+, [2M+H]+ and [2M+NH4]+. The unimolecular decomposition of the clusters can be followed by the accompanying metastable peaks.

Space Potential and Ion Energies in a Low Pressure Discharge Containing at least Two Negative Species

1988 ◽  
Vol 117 ◽  
Author(s):  
S G Ingram ◽  
N St J Braithwaite
Keyword(s):  
Energy Distribution ◽  
Collisionless Plasma ◽  
Negative Ions ◽  
Potential Drop ◽  
Low Pressure ◽  
Type Model ◽  
Plasma Parameters ◽  
Ion Energy ◽  
Ion Energy Distribution ◽  
Positive Ion

AbstractA Tonks-Langmuir type model for a one-dimensional low pressure (collisionless) plasma containing at least two species of Maxwellian negative charge carriers is examined. The solutions of this model yield the positive ion energy distribution at the sheath edge without needing to specify the ionization process. This distribution has a width consistent with the potential drop across the plasma, and is shown to satisfy the generalised Bohm criterion for sheath formation. However by assuming a form for the ionization rate in the plasma, the potential profile across the discharge has been calculated. It has been found that for a range of plasma parameters the solution for the potential at which quasineutrality fails becomes triple valued; the physical solution in this regime is identified.Many plasmas used for materials processing contain negative ions. It is important to understand how these ions influence the positive ion energy distribution at the substrate where the processing occurs.This work is also of relevance to the behaviour of Langmuir probes in electronegative plasmas.

scholarly journals Influence of the Ion Mass in the Radial to Orbital Transition in Weakly Collisional Low-Pressure Plasmas Using Cylindrical Langmuir Probes

2020 ◽  
Vol 10 (17) ◽  
pp. 5727 ◽  
Author(s):  
Guillermo Fernando Regodón ◽  
Juan Manuel Díaz-Cabrera ◽  
José Ignacio Fernández Palop ◽  
Jerónimo Ballesteros
Keyword(s):  
Free Path ◽  
Debye Length ◽  
Mean Free Path ◽  
Low Pressure ◽  
Plasma Potential ◽  
Ion Current ◽  
Ion Temperature ◽  
Langmuir Probes ◽  
The Relationship ◽  
Positive Ion

This paper presents an experimentally observed transition from the validity of the radial theories to the validity of the orbital theories that model the ion current collected by a cylindrical Langmuir probe immersed in low-pressure, low-temperature helium plasma when it is negatively biased with respect to the plasma potential, as a function of the positive ion-neutral collision mean free path to the Debye length ratio Λ=λ+/λD. The study has been also conducted on argon and neon plasmas, which allows a comparison based on the mass of the ions, although no transition has been observed for these gases. As the radial or orbital behavior of the ions is essential to establish the validity of the different sheath theories, a theoretical analysis of such a transition not only as a function of the parameters Λ and β=T+/Te, T+ and Te being the positive ion and electron temperature, respectively, but also as a function of the ion mass is provided. This study allows us to recognize the importance of the mass of the ion as the parameter that explains the transition in helium plasmas. Motivated by these theoretical arguments, a novel set of measurements has been performed to study the relationship between the Λ and β parameters in the transition that demonstrate that the effect of the ion mean free path cannot be completely ignored and also that its influence on the ion current collected by the probe is less important than the effect of the ion temperature.

Positive ion flux from a low-pressure electronegative discharge

1999 ◽  
Vol 8 (3) ◽  
pp. 457-462 ◽  
Author(s):  
T E Sheridan ◽  
P Chabert ◽  
R W Boswell
Keyword(s):  
Low Pressure ◽  
Ion Flux ◽  
Positive Ion

Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

1974 ◽  
Vol 32 ◽  
pp. 544-545
Author(s):  
L.H. Bolz ◽  
D.H. Reneker
Keyword(s):  
Power Distribution ◽  
Electrical Discharge ◽  
Dielectric Breakdown ◽  
Ionic Species ◽  
Low Pressure ◽  
Polymer Surfaces ◽  
Electrical Discharges ◽  
Adhesive Bonds ◽  
Power Distribution Lines ◽  
Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

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