Bulletin of the American Physical Society
2005 58th Gaseous Electronics Conference
Sunday–Thursday, October 16–20, 2005; San Jose, California
Session PW1: Lighting and Lasers |
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Chair: Walter Lempert, Ohio State University Room: Doubletree Hotel Pine |
Wednesday, October 19, 2005 8:00AM - 8:30AM |
PW1.00001: High Power Extreme Ultra-Violet (EUV) Light Sources for Future Lithography Invited Speaker: Extreme Ultra-Violet (EUV) lithography is most likely to be used for the production of semi-conductors from about 2009. This technology will use 13.5 nm radiation to image features of 32 nm and below. One of the potential showstoppers in the commercialisation is the availability of a compact, high power source. Roughly, 500 to 1000 W in 2$\pi $ sr and within a 2{\%} bandwidth is required. Moreover, the lifetime of the first collector mirror (located at 10 to 20 cm away from the light source) should exceed half a year in continuous operation. \newline This paper gives an overview of the latest developments in plasma-based EUV sources. In this case, transition radiation of highly ionised atoms (like Li III, O VI, Xe XI and Sn VIII to XIII) is used. There are two different schemes to achieve the high plasma temperatures (20 to 40 eV), which are necessary to reach these ionization stages: laser-produced plasmas (LPPs) and discharges. The progress within the first category seems to be limited as LPPs are roughly at the same level as five years ago. In the field of gas discharges and vacuum sparks, a lot of progress has been made recently. Especially vacuum sparks seem to offer the possibility to meet the specifications for high-volume manufacturing. [Preview Abstract] |
Wednesday, October 19, 2005 8:30AM - 8:45AM |
PW1.00002: Excitation of O$_{2}(^{1}\Delta )$ in Pulsed Radio Frequency Flowing Plasmas for Chemical Oxygen Iodine Lasers Natalia Babaeva, Ramesh Arakoni, Mark J. Kushner In chemical oxygen-iodine lasers (COIL), oscillation at 1.315 $\mu $m ($^{2}P_{1/2} \quad \to \quad ^{2}P_{3/2})$ in atomic iodine is produced by collisional excitation transfer of O$_{2}(^{1}\Delta )$ to I$_{2}$ and I. Plasma production of O$_{2}(^{1}\Delta )$ [eCOIL] is interesting to eliminate liquid phase generators. For the flowing plasmas used for eCOILs (He/O$_{2}$, a few to 10s Torr) self sustaining electron temperatures are 2-3 eV whereas excitation of O$_{2}(^{1}\Delta )$ optimizes with T$_{e}$ = 1-1.5 eV. Lowering T$_{e}$ is of interest to increase system efficiency. One method is the spiker-sustainer (S-S). A high power pulse (spiker) is followed by a lower power quasi-dc period (sustainer). Excess ionization produced by the spiker enables the sustainer to operate with a lower T$_{e}$. Results from global kinetics modeling suggest that S-S can raise yields of O$_{2}(^{1}\Delta )$ to over 30{\%}. In this paper, results from a computational investigation of radio frequency (13, 27, 56 MHz) excited flowing He/O$_{2}$ plasmas will be discussed with emphases on S-S techniques. The model is a 2-dimensional plasma hydrodynamics simulation encompassing a solution of Navier Stokes equations for neutral flow dynamics. The efficiency of S-S methods generally increase with increasing frequency by producing a higher electron density, lower T$_{e}$ and, as a consequence, a more efficient production of O$_{2}(^{1}\Delta )$. [Preview Abstract] |
Wednesday, October 19, 2005 8:45AM - 9:00AM |
PW1.00003: Plasma Kinetics of High Power Overtone Carbon Monoxide Lasers Yurii Utkin, Matthew Goshe, Igor Adamovich, Walter Lempert, J. William Rich Electric-discharge-excited carbon monoxide gas lasers, operating on either the fundamental vibrational bands (near 5 $\mu )$ or first overtone vibrational bands (near 2. 5 $\mu )$ are among the very few lasers operating at high efficiencies ($>$ 10{\%}) that are scalable to truly high c.w. powers. We report the recent development of a small compact first overtone band CO laser, together with a plasma kinetic model of the laser. Model calculations show that it is possible to build a CO laser operating on the second and higher vibrational overtone bands, with high efficiencies and powers. The possibility of lasing over a very large bandpass, extending to short IR wavelengths, is discussed. [Preview Abstract] |
Wednesday, October 19, 2005 9:00AM - 9:15AM |
PW1.00004: Color Rendering and Power Factor Trade-offs in Rare Earth Containing Ceramic Discharge Metal Halide Lamps Ray Gibson Medium power ceramic discharge metal halide lamps that contain rare earth iodides have been designed to operate on existing pulse start metal halide magnetic ballast systems intended for quartz lamps that utilize the NaI-ScI$_{3}$ salt system. One problem encountered was that the rare earth containing ceramic lamps operated well below rated power on commercial ballasts with the consequence of lower luminous flux than expected. Lower power operation is characterized electrically as a lower lamp power factor. Experiments were carried out with several different discharge tube dimensions and salt chemistries, which showed a strong correlation between color rendering (CRI) and lamp power factor. Higher CRI lamps had lower power factors. One-dimensional modeling of the arc plasma using the Elenbaas-Heller equation confirmed that by increasing the radiation contribution from the rare earth salts to model a higher lamp CRI resulted in larger swings in the central arc temperature. Consequently, a high re-ignition voltage during current reversal occurs and the lamp power factor is lowered. [Preview Abstract] |
Wednesday, October 19, 2005 9:15AM - 9:30AM |
PW1.00005: Model Study of Breakdown in Long Tubes W.J.M. Brok, J.J.A.M. van der Mullen, G.M.W. Kroesen The mechanisms responsible for the propagation of ionization waves that occur in a straight discharge tube during breakdown are studied by means of a fluid model. The discharge tube contains a gas mixture of argon at 3.0 Torr and saturated mercury vapour. The electrodes are heated to thermal emission temperatures. These conditions are similar to those found in fluorescent lamps. Firstly, operation at a dc applied voltage is investigated numerically and compared to experimental observations. Secondly, breakdown at a high frequency (tens of kHz) applied voltage is considered. It will be shown that during dc operation, the anode directed ionization wave charges the wall of the lamp and thereby shields it from outside influences on the electric field. When this wave reaches the anode, a conducting path is established between the electrodes. The subsequent cathode directed ionization wave increases the plasma density and redistributes the axial electric field towards the situation found in stationary operating discharges. During ac operation, depending on the frequency, these two processes alternate as the ionisation wave cannot cross the entire tube in a half-cycle of the applied voltage. [Preview Abstract] |
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