Noble Gas Discharges

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NOBLE GAS DISCHARGES

Raphael Mehlich 21.Juni.2010 IdIndex

 History of noble gases

 Properties of noble gases

 High pressure discharge lamps

 Glow lamps

 Noble gas excimer

Raphael Mehlich 21.Juni.2010 His tory of noble gases

 1868: Jules Janssen and Norman Lockler discov ered Helium  1892: Luigi Palmieri verified Helium  1894: LdLord RlihRayleigh has discovere d Argon  1898: Lord Rayleigh and Morris William Travers verified Neon, Xenon and KKtrypton by fftilractional dis tilla tion of air  1900: Friedrich Ernst Dorn discovered Radon  2006: UnunoctUiium was made byb theInstIiitute for NlNuclear Research and the Lawrence Livermore National Laboratory

Raphael Mehlich 21.Juni.2010 PtiProperties of noble gases

 All noble gases are odorless, colorless, nontoxic, incombustible under normal conditions and are stable in a non‐molecular state

Raphael Mehlich 21.Juni.2010 Hig h Pressure Disc harge Lamps

• Pressure of noble (Xe) gas 5‐20 bar during operation 12‐100 bar • Ignition voltage 20‐30 kV operating voltage 30 V • Distance of electrodes 0,2mm to several mm • Quantum efficiency 40 lm/Watt • Comparable to solar spectrum color temperature ~ 6000 K

Raphael Mehlich 21.Juni.2010 AlitiApplication for Disc harge Lamp

• Vis‐Spectroscopy (400‐800 nm) • Projector • Spotlight • Purification of water • Pros: ‐ bright light ‐ homogeneous spectrum (400‐800nm)

• Cons: ‐ formation of ozone ‐ short lifetime (several 1000h) ‐ high technical effort ‐ safety requirement

Raphael Mehlich 21.Juni.2010 Glow Disc harge Lamps

• Pressure of noble gas (Xe) less than 10‐2mbar • Operating voltage < 100V • Color depends on applied noble gas • Cold bulb

Raphael Mehlich 21.Juni.2010 AlitiApplications

• Adv ertisement

• Phase checker • Pros: ‐ cold bulb ‐ pure color s

Raphael Mehlich 21.Juni.2010 EiExcimers • Excimer = excited dimers

• Dimer: two noble gas atoms (Xe2*,Ar2*,…) or noble gas halides (XeF*,KrCl*) • EEixcimer are only stable in excidited state

• R* + R  R2* R+ + X‐ + M  RX* + M

R* + X2  RX* + X

Raphael Mehlich 21.Juni.2010 AlitiApplications of EiExcimer Disc harges

 Light Screens (Planon® )  Excimer Laser  High power Cold UV Excimer System

Planon®

Raphael Mehlich 21.Juni.2010 Plasma TV

 Noble gases Xe for 148 and 172 nm Ne for orange range  Excitation of Xe atoms by electron collision  UV Radiation is converted by phosphor into visible light

Raphael Mehlich 21.Juni.2010 Sources

 Hans‐Jörg Bullinger – Technologieführer, Springer Verlag, Berlin (2007)  Dieter Meschede – Gerthsen Physik, Springer Verlag, Berlin (2006)  Erwin Riedel –AnorganischeChemie, Walter de Gruyter Verlag, Berlin (2004)  Wolfgang Demtröder – Experimentalphysik 3, Springer Verlag, Berlin (2010)  Joachim Staab ‐ Industriele Gasanalyse, Oldenbourg Verlag, München (1994)

 http://www. elektronikinfo.de/strom/thermischelampen .htm  http://www.uni‐muenster.de/Physik.TD/gasentladungslampen.html  http://www.heraeus‐noblelight.com  http://www.newport.com  http://www.uni‐protokolle.de

Raphael Mehlich 21.Juni.2010