Absolute atomic chlorine densities in a Cl<sub>2</sub> inductively coupled plasma determined by two-photon laser-induced fluorescence with a new calibration method

Booth, Jean‐Paul; Azamoum, Yasmina; Sirse, Nishant; Chabert, Pascal

doi:10.1088/0022-3727/45/19/195201

Cited by 24 publications

(31 citation statements)

References 15 publications

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“…There are few examples of sufficiently detailed studies in low‐temperature plasma physics. Studies of the chlorine system represent a recent initiative in this direction, but remain a work in progress.…”

Section: Validationmentioning

confidence: 99%

Computer Simulation in Low‐Temperature Plasma Physics: Future Challenges

Turner

2016

Plasma Processes & Polymers

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Computer simulations can be carried out with various aims. Perhaps the most challenging is prediction under conditions where experiments are difficult or inaccessible, especially when failure to predict adequately may have unhappy consequences. There is, probably, not much confidence at present in the capability of low‐temperature plasma physics simulations in such a context. Other fields have attempted to meet this challenge using a collection of techniques collectively known as “Verification and Validation,” or “V&V.” These are methods for enhancing confidence in the correctness and fidelity of computer simulations. This paper surveys these techniques and discusses their application to improvements of simulation capability in low‐temperature plasma physics.

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Section: Validationmentioning

confidence: 99%

Computer Simulation in Low‐Temperature Plasma Physics: Future Challenges

Turner

2016

Plasma Processes & Polymers

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“…In this work we investigate an inductively coupled chlorine plasma [28], with focus on the role of the wall recombination probability and the gas temperature. We employ a global model in the investigation that covers both continuous and millisecond scaled modulated power inputs, while comparison with available experimental data is also provided.…”

Section: Introductionmentioning

confidence: 99%

Global (volume-averaged) model of inductively coupled chlorine plasma: Influence of Cl wall recombination and external heating on continuous and pulse-modulated plasmas

Kemaneci

Carbone

Booth

et al. 2014

Plasma Sources Sci. Technol.

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General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractAn inductively coupled radio-frequency plasma in chlorine is investigated via a global (volume-averaged) model, both in continuous and square wave modulated power input modes. After the power is switched off (in a pulsed mode) an ion-ion plasma appears. In order to model this phenomenon, a novel quasi-neutrality implementation is proposed. Several distinct Cl wall recombination probability measurements exist in the literature, and their effect on the simulation data is compared. We also investigated the effect of the gas temperature that was imposed over the range 300-1500 K, not calculated self-consistently. Comparison with published experimental data from several sources for both continuous and pulsed modes shows good agreement with the simulation results.

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“…When photons with energy exceeding the dissociation energy of molecular oxygen (5.17 eV) are absorbed by O 2 molecules, dissociation can occur resulting in two oxygen atoms. The dissociation yield for O 2 is 100 % so the atomic oxygen density produced by a laser pulse during photolysis is given by the expression [25]:…”

Section: Theory and Discussionmentioning

confidence: 99%

“…For a gas temperature of 291 K the probed level makes up ~ 74.7 % of the total ground state atomic oxygen population. Fly-out, where some of the oxygen atoms created during photolysis may exit the focal zone during the laser pulse before two-photon absorption occurs may also be an issue [25]. The laser pulse has an 8 ns duration, so the hot O atoms can travel up to 11.3 m meaning that ~ 45 % of the oxygen atoms could leave the focal zone during the laser pulse.…”

Section: Theory and Discussionmentioning

confidence: 99%

“…This significantly reduces photolytic interference effects on TALIF signals as discussed by Kulatilaka et al [23,24]. Photolysis, on the other hand, is an alternative method that can be used to calibrate TALIF experiments [25,26]. One approach involves using two lasers: one to photo-dissociate a molecular gas producing a known number density [X] Cal of the species of interest X, and a second laser to excite [X] Cal producing a TALIF signal.…”

Section: Introductionmentioning

confidence: 99%

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Two-photon absorption laser induced fluorescence measurement of atomic oxygen density in an atmospheric pressure air plasma jet

Conway

Gogna

Gaman

et al. 2016

Plasma Sources Sci. Technol.

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Photolysis:• A laser is used to dissociate O 2 molecules producing a known atomic oxygen population. The laser pulse also interacts with these O atoms over the course of the pulse causing two-photon excitation. The resulting TALIF signal is recorded. The amount of [O] produced depends on the wavelength, photon fluence and molecular O 2 density [O 2 ] the laser beam interacts with. The dissociation energy of O 2 is 5.17 eV so once the photon energy of the laser exceeds this value [O] will be generated.• Single laser shot:  = 225.6 nm (E photon = 5.5 eV) t Laser = 8 ns  Single photon absorption in the Herzberg continuum of O 2 ( = 3.21  10 -24 cm 2 at 225.6 nm ) Photo-dissociation of O 2  2 O( 3 P) atoms. Fast process (~10 -13 -10 -14 s)  Laser then excites these O atoms via 2-photon absorption  TALIF signalWhere : Photo-dissociation cross section at  Laser : Photon fluence.• Laser pulse energy E pulse : 1.2 mJ • Laser Frequency f: 1.33  10 15 Hz.• Focal spot area A: 6.03  10 -9 m 2 .As the resulting atomic oxygen density is a function of the laser energy, [O] will vary over the course of the laser pulse. The laser pulse has a Gaussian temporal behaviour so the resulting [O] generated will also vary in a Gaussian manner. Using atmospheric oxygen as our calibrating gas (atm. Pressure = 1.013  10 5 Pa, temperature = 300 K, humidity 0.45) the overall atomic oxygen density value at the end of laser pulse [O] Cal is 7.08  10 19 m -3 .• The atomic O produced by photolysis are "hot". E O(hot) = E photon(225.6 nm) -E dissociation = 5.5 -5.17 = 0.33 eV  O fragments have velocities of up to 1411 m/s so some may leave the laser focal zone before twophoton absorption occurs.• t Laser = 8 nm  O hot atoms travel ~ 11.3 m while laser on so ~ 45 % of O hot potentially lost from the focal zone over the duration of the laser pulse.However due to the small mean free path at atmospheric pressures (~ 66 nm) the root mean square diffusion distance x RMS = 4 = 9.95  10 -7 m so only ~ 4.5 % of the atomic O leave the focal zone over the duration of the laser pulse.O atoms in the red zone can potentially leave the laser focal zone and so will not contribute to the TALIF signal recorded• The hot oxygen atoms produced during photolysis will experience enhanced quenching due to their high velocities when compared with O atoms produced in the plasma. This affects the quenching factor Q which will affect the branching ratio a ij = A ij /(A + Q) for the excited state of these "hot" O atoms.

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Absolute atomic chlorine densities in a Cl₂ inductively coupled plasma determined by two-photon laser-induced fluorescence with a new calibration method

Cited by 24 publications

References 15 publications

Computer Simulation in Low‐Temperature Plasma Physics: Future Challenges

Computer Simulation in Low‐Temperature Plasma Physics: Future Challenges

Global (volume-averaged) model of inductively coupled chlorine plasma: Influence of Cl wall recombination and external heating on continuous and pulse-modulated plasmas

Two-photon absorption laser induced fluorescence measurement of atomic oxygen density in an atmospheric pressure air plasma jet

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Absolute atomic chlorine densities in a Cl2 inductively coupled plasma determined by two-photon laser-induced fluorescence with a new calibration method

Cited by 24 publications

References 15 publications

Computer Simulation in Low‐Temperature Plasma Physics: Future Challenges

Computer Simulation in Low‐Temperature Plasma Physics: Future Challenges

Global (volume-averaged) model of inductively coupled chlorine plasma: Influence of Cl wall recombination and external heating on continuous and pulse-modulated plasmas

Two-photon absorption laser induced fluorescence measurement of atomic oxygen density in an atmospheric pressure air plasma jet

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Absolute atomic chlorine densities in a Cl₂ inductively coupled plasma determined by two-photon laser-induced fluorescence with a new calibration method