Electrical characteristics of barrier discharge Tomáš Hoder In CD I Department of Physical Electronics Masaryk University, Brno, Czech Republic Gas Discharges lecture Outline ■ Historical overview Q-V plot (aka Lissajous figure) Simplest equivalent circuit of the barrier discharge Electrical current in the discharge gap vs. electrical current measured in the external circuit Voltage on the gas gap and the electric field parameter Application of the electrical analysis for the (not only) spectroscopic plasma investigation Understanding the plasma chemistry of low pressure volume and for coplanar barrier discharge in atmospheric pressure air 1 Barrier discharge - already Siemens had done it... Wenn man zwei dünne Glas- und Glimmerplatten einseitig mit Stanniol belegt und die nicht belegten Seiten so aufeinander legt, dass ein lufterfüllter Zwischenraum von geringer aber gleichmässiger Dicke sich zwischen ihnen befindet, so erhält man bekanntlich eine Licht-erscheinung in dem ganzen lufterfüllten Räume, wenn man den so gebildeten Collector durch eine hinlänglich geladene Leydner Flasche ladet. Diese Lichterscheinung wiederholt sich bei der Entladung des Collectors. Das Leuchten des Luftraums tritt nicht ein, wenn die Flasche sehr schwach geladen ist. Es beginnt bei einer ganz bestimmten Ladung und verstärkt sich von diesem Punkte an mit der Vergrösserung der Ladung der Flasche. □ fr ***** 4t 0 Uüis 1 W. Siemens 1857 and Buss 1932, Klemenc 1937, Manley 1943, Samoilovich 1966, Gibalov 1981, Eliasson, Kogelschatz 1983, Heuser 1985, Okazaki 1993, Zhu 1996, Kozlov 2001, Stollenwerk 2007 Manley and his Q-V plots for large scale ozonizers i 1 2 3 4 1 Time 3 Vi c i So r D 1 J */ / o E / 90 decree ° J / o / r* i i ' 0 *■' O KV 1 B 4 Q •ö;Qo/2»Ccei; Manley 1943 Trans. Electrochem. Soc. Kogelschatz 2003 Plasma Chem. Plasma Process. Simplest equivalent circuit of barrier discharge a macroscopic point of view c u* CD o c TO C i— CD -t—• C 7« I gap node q q dielectric node qIQo'/2'-0-"/' ......r V Q = Cce||y /// Liu et al. 2003 J. Phys. D: Appl. Phys. Pipa et al. 2012 Rev. Sci. Instrum. Kirchhoff's circuit equations and the result a macroscopic point of view c u* ud(t) = Qjt) cd UM) = V(t) - Ud(t) JR = i(t) - jgO) j8(t) = cg dU8(t) át CD "O O c "ČĎ c i— CD -t—• c c u« Jr l gap node q q dielectric node V UM) = V(t) - Qit) Ccell = Cd + ck JR(t) = i C8 1 + — cd i(t) - C 8 dV(t) át 1 - Ccell Cd L i(t) - C, cell dV(t) át 9(0 = C cell 1 - Ccell Qit) Ccell Vit) \+q0 Liu et al. 2003 J. Phys. D: Appl. Phys. Pipa et al. 2012 Rev. Sei. Instrum. Discharge current correct value? MO = i + — cd i(t) - c 8 Tschiersch et al. 2017 J. Phys. D: Appl. Phys. Peeters et al. 2015 Plasma Sources Sci. Technol. Pipa et al. 2012 Rev. Sci. Instrum. Williamson et al. 2006 J.Phys. D: Appl. Phys. dV(t) Merbahi et al. 2004 J. Phys. D: Appl. Phys. fa Liu et al. 2003 J. Phys. D: Appl. Phys. Bibinov et al. 2001 J. Phys D: Appl. Phys. 8 ^discharge (0 — ^meas(0 ^Cgas — h meas (0 - c dVgas(0 r gas dt Reichen et al. 2010 J. Phys. D: Appl. Phys. Massines et al. 2005 Plasma Phys. Control. Fusion Naude et al. 2005 J. Phys. D: Appl. Phys. Bletzinger et al. 2003 J. Phys. D: Appl. Phys. Lomaev et al. 2001 Atmos. Oceanic Optic. 7 Electrical current balance equation a microscopic point of view c, cg[ . U, it(t) = ic(x,t) +e(x)e0 dE(x,t) dt I Jo e(x) f Jo d rd+9 it(t) fd+° dx fd+9 ic(x,t)dx | = e(x)£0 dt,/ r^9 / E(x, t)dx Jo jt(t)[ —+ cd c 9 As0 J0 e(x) at jn(t) = jc(t) = 1 1 - Ccell Ca i(t) - Cceii dV(t) dt Kulikovsky 1994 J. Phys. D: Appl. Phys. Wang et al. 2006 J. Appl. Phys. Hoder, Bonaventura et al. 2016 Electrical current balance equation + surface charge a microscopic point of view U C< C_il u, I it(t) = ic(xA) + e(x) = ^(*)^o $Z — 4 at ~ Lc m ö(7 rer 0(0 + rf) 1 # + d dV dt I erg + d \ erg + d,£r£° dt g + d dV \£r£o erg + d dt Jä(*) = jc(t) = 1 - c. cell Bonaventura, Hoder et al. 2017 Limitations: net charge in streamer head and sheath 2D simulation of the volume barrier discharge in atmospheric pressure air 120 bo — 40 — red arrow denotes the streamer impact onto the cathode creating the conductive channel Braun et al. 1992 Plasma Sources Sei. Technol. Limitations: net charge in streamer head and sheath Correlated current and spatiotemporal development of helium line in barrier discharge plasma jet in atmospheric pressure helium < E 0.0 - - 1 1 1 1 V Glass tube 4 6 8 10 12 14 16 18 t [nS] the streamer impact creating the conductive channel Sretenovic et al. 2014 J. Phys. D: Appl. Phys. Limitations of current determination Coplanar barrier discharge in air at 30 kPa pressure U(V) ■measured i(t)* 10000 discharge i (t)* 10000 8200 T 8300 8400 A ~\-1-r 8500 8600 4000 3000 2000 o a > o o o o 1000 0 8700 8800 time [ns] red arrow denoting the impact of streamers on the electrodes jn(t) = jc(t) = 1 Cce.ll i(t) - a cell dV(t) dT UM) = V{t) - Q(0 Eft) = Ug(t)/g 11 Hoder, Synek et al. 2016 Plasma Phys. Control. Fusion Spectroscopic comparison - helium barrier discharge at 20kPa Spatiotemporally resolved direct electric field measurement using Stark polarization emission spectroscopy in helium volume barrier discharge 15 I-1.0 > 0.5 h ^ 0.0 £ -05 I- O > -1.0 --1.5 - 50 h(0 UM) = (0 - Cg dí/a(0 dt IJt) dr E o > •—- o 2 6 m= 4 £ 2 O 0 0) 8 LU g 4 2 0 8 6 4 2 -100 ns Anode •WM Cathode I ■ ♦♦♦♦♦♦♦♦ 0 ns Anode Cathode . 1 . +100 ns Anode Cathode I +200 ns Anode ._I Cathode +300 ns Anode 0i-.- -0.04 -0.02 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 Distance from Cathode (cm) 0.16 0.18 0.20 Figure 8. Development of the electric field spatial distribution in DBD in helium at 200 mbar. Ivkovic et al. 2009 J. Phys. D: Appl. Phys Liu et al. 2003 J. Phys. D: Appl. Phys Spectroscopic comparison - helium at 20kPa Spatiotemporally resolved direct electric field measurement using Stark polarization emission spectroscopy - comparison I) 0.03mm Gas out M = M + /t(r)_c UM - at g + Cd C{ 77T f'iWdl + <-d JO ~ -800 -4.0 8.0 8.5 9.0 9.5 10.0 10.5 Time ((.is) 11.0 11.5 12.0 Figure 10. Comparison of calculated cathode fall voltage f/cai and measured gap voltage Ue in the DBD at 200 mbar pressure. Ivkovic et al. 2009 J. Phys. D: Appl. Phy Liu et al. 2003 J. Phys. D: Appl. Phy Spectroscopic comparison - N2/H2 mixture at atmospheric pressure in ns-pulsed barrier discharge derived within the simplest equivalent circuit approach Direct electric field measurement in the discharge gap based on coherent anti-Stokes Raman spectroscopy four-wave mixing method ■ Applied Voltage Electric Field (Absolute Value) Current 0.25 - 0.20 0.15 0.10 <5 c =3 u - 0.05 0.00 Time {[is) Boehm et al. 2016 Plasma Sources Sci. Technol. Kettlitz et al. 2012 J. Phys. D: Appl. Phys. Pipa et al. 2012 Rev. Sci. Instrum. Spectroscopic comparison - air 30kPa Townsend phase of coplanar barrier discharge prior the breakdown Effective electric field determined by Townsend alpha coefficient fitting of a(E/N) from high-resolution emission of N2(C-B) in coplanar barrier discharge 0.10 derived within the simplest equivalent circuit approach 500- applied voltage gap voltage measured current-| 0.08 discharge current -I 0.06 o c —i CD A 0.04 — - 0.02 0.00 200 400 600 time [ns] 800 1000 Electric field at the breakdown instant: 190±30 Td (electrics) and 220±20 Td (fitting) and 210±40 Td from FNS/SPS(E/N) Pipa et al. 2012 Rev. Sei. Instrum. Hoder, Synek et al. 2016 Plasma Phys. Control. Fusion Pockels effect comparison - helium barrier discharge at atmospheric pressure Electric field measurement induced by Pockels effect on deposited surface charge Glass plate with ITO layer BSO crystal Isolation plates Aluminium mirror dUa(t) /g(0 = ll + ^j/,(0-CE— q(t) = C cell 1 - Ccell 6(0 _ Ccell -V(t) o o I! 4s{ 0 O -0 -0 -0 O Measured surface charge Temporally integrated net current 100 200 300 t(M5] 400 Bogaczyk, Sretenovic et al. 2012 Eur. Phys. J. D Liu et al. 2003 J. Phys. D: Appl. Phys. Determination of capacitances - fully powered large scale reactors (DCSBD, ozonizers,...) Limited just for full electrode surface /J /£ coverage by plasma! E.g. DCSBD at power with full coverage of electrodes by plasma filaments! Falkenstein et al. 1997 J. Phys. D: appl. Phys. Manley 1943 Trans. Electrochem. Soc. Peeters et al. 2015 Plasma Sources Sei. Technol. Pipa et al. 2012 Rev. Sei. Instrum. Determination of capacitances - pulsed reactors Low pressure asymmetric barrier discharge in argon at 100 mbar Atmospheric pressure symmetric barrier discharge in N2-02 mixture 01 23456789 10 11 V[kV] 115 u C 2.5 2.0 1.5 1.0 0.5 0.0 I ' I ' I ■ I ■ I < i Cd = (0.34 ± 0.02) pF - ***** hf - i i i . i < i i i 4 6 V/kV ßmax — (Vmax Ures) HV probe 8 10 18 Pipa et al. 2012 Rev. Sei. Instrum. Applicability of the approach - limitations C ue CD TD O cz "cö c B c c u- Jr gap node „ q dielectric node V l l - c cell m - c, dV(0 cell dt q(t) = C cell l - Cre. cell Qjt) L Ccell Ug(t) = V(t) - -V(t) 0(0 19 Limited to barrier discharges which can be described within a single node approximation - i.e. the radial structure is negligible for given spatial- and temporal-scale: 1. Homogeneous barrier discharges (pulsed or sine applied voltage) 2. Nanosecond pulsed barrier discharges 3. Spatially confined single-filament barrier discharges 4. Multi-filament plasma sources with full electrode coverage Liu et al. 2003 J. Phys. D: Appl. Phys. Pipa et al. 2012 Rev. Sei. Instrum. What about not fully powered barrier discharge reactors ... ? or middle-sized multifilament discharges without full surface coverage by plasma - what to do? V(t) i(t) ô o aQ orC gap aQ call I ßc< J plasma ( 0 ugaP(t) plasma (0 — 1 1 — Qell/Qiel _ 'dß(f) _ dV(t) - <-cell dt at 0(0 = ( 1 - ^ ) ßplasmaW +CcellV(i) <-diel / ^w(0 = (l + |^|V(0- P C diel. JÖC, ß(0. O 1.5 1.0 0.5 _ 0.0 O -0.5 -1.0 -1.5 1 I 1 I 1 // // // i i i i i S s' * 'S S s s f / / s 7 — S ' y 'V Á?, y .-y / /y / s/' / i , i *' ŕ'/ // '/ Voltage amplitude (kV) _ --4.2 -----8.4 10.1 -----11.1 -11.6 i . i 15 -10 -5 0 10 15 diel V(kV) Peeters et al. 2015 Plasma Sources Sei. Technol. How to use this? What parameters can be approached.. ... besides the cases for mentioned spectroscopy and Pockels effect cases R(t) = 1 1 - C cell i(0 - C cell dV(t) dt The upper estimate of the electron density development within the established discharge channel eE(t)fie(E(t)/N) Ug{t) = V(t) - 6(0 Ca P(t) = jR(t)U9(t) Instantaneous discharge power development Averaged, spatially unresolved, electric field strength development E(t) = Ug(t)/g Effective electric field and power in ns-pulsed single-filament coplanar barrier discharge Complete analysis of macroscopic parameters of nanosecond pulsed plasma in atmospheric pressure argon gap voltage (left) and reduced el. field (right) current in the gap i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i— i -40 -20 0 20 40 60 80 100 120 140 160 180 200 1 100-, - 180 - 160 80- - 140 —. CD Cu - 120 uced i _ 60- - 100 CD O i—h -80 ric fiel '5b Ö 40- -60 a. -40 H a. 20- -20 - -0 0- 30 - 25 - 20 3 a Q- 15 g. 05 - 10 - 5 time [ns] 1 i 1 i 1 i 1—i—1—i—■—i—1—i—1—i—1—i—1—i—1—r -40 -20 0 20 40 60 80 100 120 140 160 180 200 time [ns] Gap voltage, effective reduced electric field and internal discharge current development Instantaneous development of the internal transferred charge, energy and power in the discharge Compare to Leiweke et al 2013 J. Appl. Phys. 22 Dedrick et al. 2012 Plasma Sources Sci. Technol V Hoder, Simek et al. 2017 Electron density in ns-pulsed single-filament coplanar barrier discharge Rough estimate of lower and upper limit of electron density by line-ratio and electrical methods 22 10 -. VI C o 19 10 — . 1 1 1 1 1 1 1 i 1 ■ i i i i i i i ^—•----" — / \ f electron density from electrical measurements □ electron density from line ratio I □ □ I - n breakdown process i i i i 1 i i Vi established channel ■ i i i i 1 i i i i 20 25 30 time [ns] 35 40 Other limitation of the method probably reached -plasma channel with high electron density would have less capacitive behaviour as Cg Hoder, Simek et al. 2017 Compare to Walsh et al 2010 Eur. Phys. J. D Zhu and Pu 2010 J. Phys. D: Appl. Phys. Electric field in Townsend phase of coplanar barrier discharge in atmospheric pressure air Electric field prior the breakdown from Townsend a(E/N) coefficient fitting on N2(C-B) spectra emission 100 Š CO s- o ■ — — a. CO C "Í 15 d 5b CO fit a(E/N)/N = 3.7- 10"i8cm2 resulting in E/N = 185 Td 80 60- 40 20- cathode anode 0 y T T T 0.26 0.28 0.30 0.32 0.34 0.36 interelectrode axis [cm] 0.38 0.40 6000 4000 > 00 ^ 2000 o > -2000 Electric field in the gap from electrical analysis gap voltage • applied voltage ■ measured current 24 Electric field at the breakdown instant: 180±30 Td (electrics) and 185±20 Td (fitting) and 200±40 Td from FNS/SPS(E/N) Hoder, Jánsky, Bessiéres et al. 2016 Importance of basic plasma parameters for long-term chemistry (4torr volume BD streamer) E(x,t) EVDF(x,t) rate coefficients (x,t) [^> electron, radical, metastable densities (x,t) electric field electrons 25 -5 0 5 radial position [mm] oxygen atoms NO molecules -5 0 5 radial position [mm] Hoder, Bonaventura et al. 2016 Plasma Sources Sci. Technol. Take-home message ■ Although spatially unresolved and approximative, the electrical analysis according to the simplest equivalent circuit approach can give important informations about the plasma for (not only) low-density confined plasmas. It can gives information about temporal development of the effective electric field in the discharge gap, about the net transferred charge or electron density within the plasma channel or the instantaneous consumed power in the plasma. All these derived informations can support other methods applied to investigation of the plasma. For precise analysis an, at least, 2D numerical model for given conditions has to be utilised. Single-filament coplanar barrier discharge was studied numerically and experimentally resulting in electric field high-resolution records in quantitative agreement. We plan to compute the generated surface gas chemistry using novel kinetic model of Zdenek Bonaventura including usage of sensitivity analysis. 27 Thank you for your attention! «3 > ^msfy J.K |M) Z. Bonaventura, P. Synek, V J. RáheP and M.Cernák •5s »§4 J. Jánský M. Simek D. Bessieres and J. Paillol A. Pipa Greifswald "3 CSIC F.J. Gordillo-Vazquez IVERSITE DE PAU ET DES PAYS DE L'ADOUR ... and thanks to my colleagues and collaborators for the fruitfull discussions and their contribution! Streamer impact and channel current 2D simulation of the volume barrier discharge in atmospheric pressure air 120 bo — 40 — red arrow denotes the streamer impact onto the cathode creating the conductive channel 9 Braun et al. 1992 Plasma Sources Sei. Technol. Pre-breakdown phase of pulsed BDs: different pulse widths Electrical characteristics 10.0 > 5.0 2.5 0.0 0 20 40 ! I ! [ ' , Rising Fall ing pe ♦ — 50 ps j slooe Fuss ■ sic t = 10 MS 1 50 ps l ■ 4 ■ 1 ________ ________ ------- j i - I .......f...... 1 ------- ........ -------i------ ] --------j.-------- -------- -------- ------- -------1------- ■ ------- ------- ------- -------1------- - 200 0 60 80 t/jJS 100 120 140 -200 TC-SPC recording at the anode »> new-found local maximum emerging prior to the breakdown of the gap 6 Hoeft et al. 2014 J.Phys.D:Appl.Phys. Emission spectra and E/n determination 50000 40000 2 30000 CD o rb .......1 ■ CD 103 1 5 10 4 -I o 10"5j OJ 1 ■ CO > CD 10"2] 1031 10 : j io5: 14 EBE and MC results agree well and coincide with the corresponding steady-state electron distribution function components ^ equilibrium values are reached after 10 ps and 5 jim. Other approach is the study of the electron relaxation in time and space for different reduced electric field strengths E/N: lines represent f0, f1 after 10 ps of the temporal electron relaxation (solution of the electron Boltzman equation in multi-term approximation). symbols denote f0, f1 for the ID spatial relaxation of electrons after a distance of 5 jim using the Monte Carlo method. Hoder, Loffhagen 2016 PSST E[kVcm-i] v*x ^k[1013R] Sources [1023 cnrV1] Density [1013 cm"3] M 4^ Ol OD O M ° ° ° ° ° POPMWJi^OlvimMPOPMtOJiülOlO H> 1*0 CO .p. Ü1 Ol ooooooö ro 4^ c) co bbbbbbbbbböbbbbbbbböbbbbbb um{v) = NvQT(v) Am (v) 1 NQT(v) Ae(u) = Xm(v) \J 3ue(v] VM = Nv ( ^Qd(v) vT Loffhagen2015