jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 Feb 2007

Volume 101, Issue 4, Articles (04xxxx)

Return to All Sections
back to top
RSS Feeds

Simplified calculation of nonlocal thermodynamic equilibrium excited state populations contributing to 13.5 nm emission in a tin plasma

J. White, A. Cummings, P. Dunne, P. Hayden, and G. O’Sullivan

J. Appl. Phys. 101, 043301 (2007); http://dx.doi.org/10.1063/1.2434965 (14 pages) | Cited 9 times

Online Publication Date: 16 February 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Extreme ultraviolet lithography schemes for the semiconductor industry are currently based on coupling radiation from a plasma source into a 2% bandwidth at 13.5 nm (91.8 eV). In this paper, we consider the case for a laser-produced plasma (LPP) and address the calculation of ionic level populations in the 4p64dN, 4p64dN−14f1, 4p54dN+1, and 4p64dN−15p1 configurations in a range of tin ions (Sn6+ to Sn13+) producing radiation in this bandwidth. The LPP is modeled using a one-dimensional hydrodynamics code, which uses a hydrogenic, average atom model, where the level populations are treated as l degenerate. Hartree-Fock calculations are used to remove the l degeneracy and an energy functional method to calculate the nl level populations involved in n = 4−4 transitions as a function of distance from the target surface and time. Detailed data are presented for the tin ions that contribute to in-band emission.
Show PACS
52.25.Kn Thermodynamics of plasmas
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
47.85.Dh Hydrodynamics, hydraulics, hydrostatics
52.30.-q Plasma dynamics and flow

Numerical study of nanosecond laser interactions with micro-sized single droplets and sprays of xenon

T. Auguste, F. de Gaufridy de Dortan, T. Ceccotti, J. F. Hergott, O. Sublemontier, D. Descamps, and M. Schmidt

J. Appl. Phys. 101, 043302 (2007); http://dx.doi.org/10.1063/1.2432870 (13 pages)

Online Publication Date: 20 February 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a thorough numerical study on interactions of a nanosecond laser with micro-sized xenon droplets. We developed a code which allows simulation of laser interactions with a single droplet as well as a spray. We give a detailed description of the code, and we present results on the dynamics of a microplasma produced by irradiation of a single xenon droplet with a laser focused at peak vacuum intensity in the 5×1010−5×1012 W/cm2 range. We find that the heating of the plasma depends dramatically on the laser parameters (duration, pulse shape, and intensity) on one hand, and on the droplet diameter on the other. We also present results obtained with a spray which show that the dynamics of the microplasmas is very sensitive to the position of the droplets in the interaction volume. The predictions of our model agree well with recent experimental observations performed on laser-produced plasma sources for extreme ultraviolet lithography. In particular, the postprocessing of our data with a sophisticated atomic physics code has allowed us to reproduce quite well the spectrum emitted in the extreme ultraviolet range by a xenon plasma generated by laser irradiation of a spray of droplets.
Show PACS
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.50.Dg Plasma sources

Numerical study on xenon positive column discharges of mercury-free lamp

Jiting Ouyang, Feng He, Jinsong Miao, Jianqi Wang, and Wenbo Hu

J. Appl. Phys. 101, 043303 (2007); http://dx.doi.org/10.1063/1.2432024 (7 pages) | Cited 12 times

Online Publication Date: 23 February 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this paper, the numerical study has been performed on the xenon positive column discharges of mercury-free fluorescent lamp. The plasma discharge characteristics are analyzed by numerical simulation based on two-dimensional fluid model. The effects of cell geometry, such as the dielectric layer, the electrode width, the electrode gap, and the cell height, and the filling gas including the pressure and the xenon percentage are investigated in terms of discharge current and discharge efficiency. The results show that a long transient positive column will form in the xenon lamp when applying ac sinusoidal power and the lamp can operate in a large range of voltage and frequency. The front dielectric layer of the cell plays an important role in the xenon lamp while the back layer has little effect. The ratio of electrode gap to cell height should be large to achieve a long positive column xenon lamp and higher efficiency. Increase of pressure or xenon concentration results in an increase of discharge efficiency and voltage. The discussions will be helpful for the design of commercial xenon lamp cells.
Show PACS
52.80.Yr Discharges for spectral sources (including inductively coupled plasma)
52.65.Kj Magnetohydrodynamic and fluid equation
52.40.Hf Plasma-material interactions; boundary layer effects
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

Charge-state-resolved ion energy distribution functions of cathodic vacuum arcs: A study involving the plasma potential and biased plasmas

André Anders and Efim Oks

J. Appl. Phys. 101, 043304 (2007); http://dx.doi.org/10.1063/1.2561226 (6 pages) | Cited 3 times

Online Publication Date: 23 February 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Charge-state-resolved ion energy distribution functions were measured for pulsed cathodic arcs taking the sheath into account that formed between the plasma and the entrance of a combined energy and mass spectrometer. An electron emitting probe was employed to independently determine the plasma potential. All results were obtained by averaging over several individual measurements because the instantaneous energy distributions and the plasma potential show large amplitude fluctuations due to the explosive nature of the arc plasma generation. It was found that the ion energy distribution functions in the plasma were independent of the ion charge state. This is in contrast to findings with continuously operating, direct-current arcs that employ a magnetic field at the cathode to steer the cathode spot motion. The different findings indicate the important role of the magnetic steering field for the plasma properties of direct-current arcs. The results are further supported by experiments with “biased plasmas” obtained by shifting the potential of the anode. Finally, it was shown that the ion energy distributions were broader and shifted to higher energy at the beginning of each arc pulse. The characteristic time for relaxation to steady state distributions is about 100 μs.
Show PACS
52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.80.Vp Discharge in vacuum
52.50.Dg Plasma sources
52.40.Kh Plasma sheaths
52.70.Ds Electric and magnetic measurements
52.25.Gj Fluctuation and chaos phenomena
52.25.Fi Transport properties

Detailed study of the plasma-activated catalytic generation of ammonia in N2-H2 plasmas

J. H. van Helden, W. Wagemans, G. Yagci, R. A. B. Zijlmans, D. C. Schram, R. Engeln, G. Lombardi, G. D. Stancu, and J. Röpcke

J. Appl. Phys. 101, 043305 (2007); http://dx.doi.org/10.1063/1.2645828 (12 pages) | Cited 9 times

Online Publication Date: 27 February 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated the efficiency and formation mechanism of ammonia generation in recombining plasmas generated from mixtures of N2 and H2 under various plasma conditions. In contrast to the Haber-Bosch process, in which the molecules are dissociated on a catalytic surface, under these plasma conditions the precursor molecules, N2 and H2, are already dissociated in the gas phase. Surfaces are thus exposed to large fluxes of atomic N and H radicals. The ammonia production turns out to be strongly dependent on the fluxes of atomic N and H radicals to the surface. By optimizing the atomic N and H fluxes to the surface using an atomic nitrogen and hydrogen source ammonia can be formed efficiently, i.e., more than 10% of the total background pressure is measured to be ammonia. The results obtained show a strong similarity with results reported in literature, which were explained by the production of ammonia at the surface by stepwise addition reactions between adsorbed nitrogen and hydrogen containing radicals at the surface and incoming N and H containing radicals. Furthermore, our results indicate that the ammonia production is independent of wall material. The high fluxes of N and H radicals in our experiments result in a passivated surface, and the actual chemistry, leading to the formation of ammonia, takes place in an additional layer on top of this passivated surface.
Show PACS
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
82.30.Cf Atom and radical reactions; chain reactions; molecule-molecule reactions
82.30.Nr Association, addition, insertion, cluster formation
82.20.Hf Product distribution

Probing of a surface plasma wave by an obliquely incident laser on the metal surface

D. B. Singh, Gagan Kumar, and V. K. Tripathi

J. Appl. Phys. 101, 043306 (2007); http://dx.doi.org/10.1063/1.2472281 (4 pages)

Online Publication Date: 28 February 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A surface plasma wave (SPW) of frequency ω1 and wave number k1 propagating along a metal-free space boundary exerts a ponderomotive force on the free electrons, creating an electron density perturbation at frequency 2ω1. When a laser of frequency ω2 and wave number k2 is incident at a suitable angle on the metal surface, it gives rise to the oscillatory velocity of electrons at frequency ω2. This oscillatory velocity couples with the density perturbation to generate a nonlinear current at frequency 2ω1+ω2. The nonlinear current derives a radiating wave under suitable conditions. By measuring the amplitude of the radiating wave, the SPW field can be probed.
Show PACS
52.38.Dx Laser light absorption in plasmas (collisional, parametric, etc.)
52.40.Hf Plasma-material interactions; boundary layer effects
52.35.Mw Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)
52.35.Fp Electrostatic waves and oscillations (e.g., ion-acoustic waves)
52.25.Fi Transport properties
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close