Efficient stimulated emission from a microwave-pumped XeCl laser

Microwave discharges have been used to excite rare gas halide mixtures like XeC1. For the realization of microwave excited excimer lasers a minimum specific pump power density of 100 kW/cxn3 is needed. The resulting power requirements are of the order of one to ten megawatts. This power has to be deposited in a discharge tube which is housed in a hollow waveguide. For these purposes, a WR-650 waveguide circuit was assembled. The pulsed microwave source was a magnetron transmitter with a frequency of 1.35 GHz, a pulsed power of 2.5 MW and a pulse length of 4 jis. The puise repetition frequency was 10 Hz. A double ridge waveguide coupling structure was designed using the cornputer code URMEL-T. This program is based on a finite difference discretization method for the Maxwell field equations to compute electromagnetic fields in waveguides and cavities. The laser gas mixture consisted of He/Xe/HC1 = 1000/1/0.2 at a total pressure of 1000 mbar. A laser pulse energy of 20 pJ with a pulse width of 65 ns (FWHM) was measured yielding a peak power of 300 W.

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“…The design is scalable to microwave powers of the order of 100 MW without significant changes. 5 . ACKNOWLEDGEMENTS…”

Section: Theoretical Evaluation Of the Coupling Structurementioning

confidence: 95%

<title>Microwave excitation of a XeCl laser without preionization</title>

Klingenberg¹,

Gekat²,

Spindler³

1990

SPIE Proceedings

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“…A possible way of achieving this would be to compensate for the significant decrease of power flow from the power input side to the matched load side that shows up with increased applicator lengths by gradually reducing the cross‐sectional dimensions of the applicator structure, as already proposed by Zakrzewski and Moisan8 in the general case of a long linear field‐applicator. In the specific case of a plasma column lying longitudinally within a rectangular waveguide, Slinko et al9 suggested gradually reducing the waveguide height in the power flow direction. A second possible solution would be to switch the HF power feeding port with that of the matched load at half process time.…”

Section: Introductionmentioning

confidence: 99%

Plasma Sterilisation within Long and Narrow Bore Dielectric Tubes Contaminated with Stacked Bacterial Spores

Pollak

Moisan

Kéroack

et al. 2007

Plasma Processes & Polymers

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Catheters, which comprise small diameter (≤4 mm), long (typically more than a meter), thermosensitive polymer tubings, are generally used only once. This is because conventional low temperature sterilisation techniques are considered inadequate for used catheters. The plasma sterilisation method proposed in the current paper should allow for the achievement of re‐sterilisation of catheters according to accepted regulations. The plasma process described enables one to sterilise, in less than 10 min, the inner part of a long 4 mm i.d. Teflon tube contaminated initially with 106 Bacillus atrophaeus spores. This result was obtained by achieving an argon discharge at reduced pressure (750 mTorr) within the hollow (dielectric) tube itself. The discharge was sustained using a microwave field‐applicator called a stripline, fully enclosing the tube to be treated. This linear field‐applicator yields a uniform plasma all along the tube, hence the uniform biocide action. The biocide agents are the vacuum ultra‐violet (VUV) photons, which include oxygen and nitrogen atomic lines, the N2 Lyman‐Birge‐Hopfield (LBH) bands, the UV photons emitted by the NOβ and NOγ molecular systems resulting from the contamination, even though at a very low‐level, of the argon gas (high purity argon is used) by air. Scanning electron microscopy (SEM) revealed no apparent damage to the external structure of the spores and to polystyrene microspheres exposed to plasma during the time required for reaching sterility. To check for sterility in such narrow bore tubes without having to cut them into two pieces, a procedure was developed to introduce and afterwards collect the bacterial spores used as bio‐indicators. This diagnostic procedure allowed, at the same time, the imaging of the microorganisms relatively efficiently with SEM, showing the eventual stacking of bacterial spores, a possible source of sterilisation failure.

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XeCl laser excitation by high power microwave pulses

Klingenberg

Gekat

1992

Appl. Phys. B

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Efficient stimulated emission from a microwave-pumped XeCl laser

Cited by 6 publications

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<title>Microwave excitation of a XeCl laser without preionization</title>

<title>Microwave excitation of a XeCl laser without preionization</title>

Plasma Sterilisation within Long and Narrow Bore Dielectric Tubes Contaminated with Stacked Bacterial Spores

XeCl laser excitation by high power microwave pulses

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