DD157138A1 - ENDING DEVICE FOR ARC FLASH PLASMATRONS AND LONG LIGHT BOLTS WITH RELATIVELY LARGE ELECTRODE DEFAULT - Google Patents

Abstract

The invention Zuendvorrichtung for arc plasmatrons and long gasbestroemte Lichtboegen with relatively large Elektrodenabstaenden refers to Lichtboegen and Plasmatrons when using washers or other serving as auxiliary electrodes components. The object of the invention is the safe ignition of long arcades of light in any gases, without secondary and short circuits and the ignition process causing or preventing electrical voltage reductions between electrodes and auxiliary electrodes. Thermal overloads of the auxiliary electrodes and Nebenstroeme after arc flashover are prevented by selbstaetiges switching off the Zuendvorrichtung. According to the invention this is done in various circuit variants by passing through a pilot arc over all auxiliary electrodes to the second electrode, which prevents by diodes Nebenstroeme between auxiliary electrodes with each other and to electrodes, optimal voltage differences between these components achieved and the entire Zuendvorrichtung be switched off after the end of the arc of a Schaltschuetz , The invention is applicable to all plasma technology purposes, in particular for gas heating and plasma chemistry.

Description

T itel of the invention .

Ignition device for arc plasmatrons and long arc with relatively large electrode distances

Field of application of the invention

The invention relates to an electric ignition device for arc plasma and long, preferably wall, disc or vortex stabilized, with the working gas flowed arc with relatively large electrode intervals for ignition from the electrical idling of the arc voltage source in a possible use of electrically conductive, against each other electrically insulated intermediate disks with central hole, rings or rods as auxiliary electrodes for the arc ignition between the electrodes for the purposes of gas heating, plasma chemistry, plasma spraying, plasma melting, plasma diagnostics and similar applications in plasma technology, plasma technology and plasma research. _ 2 ~

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Characteristic of the known technical solutions

There are known electrical ignition devices for long arcs and Lichfbogen Plasmatrons with relatively large electrode intervals for ignition from the electrical idling of the arc voltage source with the technical solutions described below; 33s is known to ignite long arcs by means of pilot arcs, which in turn are fired with HP pulse or RF sustain discharges, e.g. See, for example, GDR Patent Nos. 103,359 and 110,600, U.S. Patent No. 2,990,466, Federal Republic of Germany Patent Specification No. 1,440,626, West German Patent Application No. 2,830,579. "The lack of such pilot arcs is their too short firing range for the main arc, especially in molecular gases, eg. In hydrogen. The reduction of this defect is possible in special arrangements, for. Example, in the presence vofr several electrodes in Mehrphasenstromplasmatrons by using multiple RF ignition circuits according to GDR Patent No. 95 058 or by using an RF igniter and introducing a Zündscheibe between two electrodes according to GDR Patent No. 110 599 and 110 600th Thus are either only multiphase and Mehrelektrodenplasmatrons or Zweielektrodenplasmatrons with an intermediate disc and therefore ignitable with only a relatively short arc length.

In addition, it is known to ignite a pilot arc sequence via a plurality of intermediate electrodes or intermediate disks acting as intermediate electrodes with active resistances connected thereto or combinations of effective resistors with capacitors. The resistors or capacitance / capacitor combinations have the same or stepped values and are connected to each other in parallel to an end electrode of the arc, preferably to the anode. Examples include the DDR patent no. 31 337 and the reference :, G. Boldt,

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K. H. Stephan, Z. angev ». Pays. 22 (1967) 429-432. These known arc ignitions by means of pilot arc sequences have as defects possible shunts tin arc on the Widerstendsschaltung adjacent washers and thus the possible short circuit of the main arc on adjacent washers and when using capacitors for many arrangements and molecular gases too short flow time of the charging currents through the individual intermediate electrodes and thus insufficient ionization of the interstices to the next intermediate electrodes and the absence or severance of the pilot arc ignition,

Furthermore, an ignition device according to DDR patent no. 137 674 is known in which a trigger spark gap a pilot arc of an electrode, for. As the cathode, generated to a Zündscheibe whose plasma and breakdown voltage allows the ignition to the next intermediate electrode, with a fixed inductance capacitance Reihensehaltung (LC series circuit) with the second electrode, z. B. the anode is connected. This circuit is to allow the ignition to the second electrode. The lack of this igniter is the too small possible Durchzündlänge over a maximum of two consecutive pilot arc sections, because the LC circuit results in low ignition energies at the required time.

Finally, according to US Pat. No. 3,007,030 and FRP Laid-Open No. 2,614,152, it is known to transform firing pulse voltages into an arc circuit via a pulse transformer. The present in the context of the present invention is the use of special and additional necessary components, eg. B. a pulse transformer, for the Zündimpulsübertragung in the arc circuit.

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The object of the invention is and it causes compared to the previously known technical solutions, the safe ignition of long arcs in any gases without principle lent limitation of the arc total length in Plasmatrons or plasma torches or other discharge vessels _s without lifting currents and thus without side and short circuits between auxiliary electrodes and Intermediate disks · during the ignition process and thereafter · The invention also reduces the annoying annoying or impossible reductions in electrical voltage differences between the electrodes and auxiliary electrodes _e 'It also allows the arc ignition with a minimum difference between the long arc and open circuit and operating voltage it causes the immediate shutdown of the ignition device after the arc ignition

- The technical task

The invention is based on the object _$ flow-type long arc through successive time and place following, from one electrode via auxiliary electrodes or intermediate discs ignited pilot arc to a second electrode to ignite reliably and continuously without interruption. ¹ The ignition should be such that no love currents on the auxiliary electrodes and shims connected to the necessary potential distribution along the arc gap serving resistors and thus directly between electrodes, auxiliary electrodes and washers can occur "- So these side streams can not be used as causes for technical Defects in the form of short circuits and shunts during the ignition process and then between electrodes, auxiliary electrodes and washers, so as

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Cause of disturbances and preventions of the ignition process and as a cause for the reduction of the voltage differences required for the ignition between the electrodes and auxiliary electrodes by electrical potential changes during the ignition process act. The invention is also based on the object to avoid unnecessary electrical and thus thermal loads on the auxiliary electrodes and components used by flowing over the resistances currents by the entire ignition immediately after ignition of the arc, and if necessary, the individual auxiliary electrodes, after ignition and translating the pilot arc to the respective next auxiliary electrode, preferably switched off by the action of the arc current »

Features of the invention

According to the invention, this object is achieved as follows:

Between two relatively widely spaced rod or hollow electrodes are located to fix and stabilize the arc column electrically conductive, against each other and against the electrodes electrically isolated washers with central hole or rod or annular components that can be used as auxiliary electrodes * On each of these washers or some of them used as auxiliary electrodes, or special auxiliary electrodes without or with an equal or different number of washers, also called neutrons, or other components are resistors, diodes or other rectifiers _for capacitors , Switches and contactors are electrically energized in one of the following switching variants, 'Their common characteristics are the use of effective resistors

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Limiting the respective pilot arc current intensity, diodes to prevent shunts between the auxiliary electrodes or the electrodes and auxiliary electrodes and switches or contactors, immediately after the arc ignition, the auxiliary electrodes in total or individually and the ignitor off

In the first circuit variant, an active resistor and a negative pole connected to the auxiliary electrode diode is connected in series at each auxiliary electrode except the first, preferably the kathodennächsten the auxiliary electrode «The diode has a surge protection circuit, for example in the form of a capacitor connected in parallel * At the first auxiliary electrode is only a resistance and no diode connected. '' The individual switching groups thus obtained are connected in parallel to each other at the ends remote from the auxiliary electrodes' The entire parallel circuit is connected via a switching contact to an electrode, preferably to the anode ₉ , the switching contact is of a contactor connected in the circuit of the arc between the power source and this electrode with normally closed contacts between the two electrodes is the Stx'omquelle for the arc ζ * Β «, a rectifier system, connected Zwi rule of the electrode to which no switch contact is connected, preferably the cathode, and its adjacent first auxiliary electrode is connected an ignition device, for _e B _0, a commercially available 100 Hz pulse or high-frequency pulse ignitor "It contains in its power supply circuit a switch contact, which by the contactor in the arc circuit is actuated «.

In the second circuit variant, with the exception of the first auxiliary electrode already mentioned, a diode with an overvoltage protection circuit, for example in the form of a capacitor connected in parallel with it, is connected to each auxiliary electrode at a negative pole. On the positive pole side, adjacent diodes each have an effective resistance.

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is connected conductively, ¹ The first auxiliary electrode is connected only via an effective resistance to the positive pole side of the diode connected to the second auxiliary electrode. The positive pole connection of the last, preferably anode-adjacent diode is connected via an effective resistor and a switching contact arranged in series to the adjacent electrode, preferably to the anode, switched «, the rest of the circuit is equal to the first circuit variant»

In the third circuit variant, a resistive resistor is connected to each auxiliary electrode. Between the free ends of adjacent resistors which are remote from the auxiliary electrodes, a diode is connected to a surge protection circuit such that its negative pole points in the direction of the pilot arc-firing sequence, preferably from anode-distal to anode-proximate Auxiliary electrode ^ The second electrode, preferably the anode, is connected to the active resistance connected to the first auxiliary electrode via a switching contact. The remainder of the circuit is equal to the first circuit variant _β

Weitexiain the circuit variants described are also to be designed so that instead of connected to the first auxiliary electrode resistance or a resistance diode combination between the first and second auxiliary electrode connected a capacitor connected in parallel, relatively high resistance as a discharge resistance and / or that at oeder the a circuit is connected between the power source of the arc and the first electrode, preferably the cathode, a choke coil as smoothing inductor * 'On the choke coil or on a part of it an auxiliary winding is applied.

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The function of the first variant of the invention is? When Lichfbogenstromqnelle connected between the electrodes, ignited ignition device zö / of the first electrode ₉ preferably the Eat ode, tmd the first, d _e 'h _e "of herin closest arranged auxiliary electrode and with closed switching contact between the second electrode, preferably the anode , and the connected to the auxiliary electrodes resistors and diodes, when the ignition device is turned on, an electrical breakdown between the first electrode, preferably the cathode, and the first, before the ignition as all other auxiliary electrodes at the electric potential of the second electrode, preferably The breakdown ignites the pilot arc between the first electrode _$, preferably the cathode, and the first auxiliary electrode. Its electrical current is boosted by the resistive resistor connected to the first auxiliary electrode or by using a capacitor charging resistor After the ignition of this pilot arc, the second auxiliary electrode, like all other auxiliary electrodes, is still at the electrical potential of the second electrode, preferably the anode ©. The plasma flowing through the pilot arc is between the first in the gas space and the second auxiliary electrode generates a sufficient electrical conductivity, so that the operating voltage minus the voltage component dropping across the existing pilot arc ignites the pilot arc to the second auxiliary electrode. The negative pole connected to the second auxiliary electrode prevents an electrical current flow between the first and second auxiliary electrodes via the second auxiliary electrode connected active resistances, so that a secondary connection to the pilot arc and thereby a possible short circuit between the auxiliary

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electrodes _e ^! The cross-ignition operation described above is repeated thereafter for the third auxiliary electrode and the further auxiliary electrode to the second electrode _s is preferably the anode ^"1 connected to the Hilfselektroderi diodes thereby prevent the occurrence of in series partial arcs between the auxiliary electrodes and possibly interposed washers or other This is an essential feature of the invention, ¹ The electrical current and power load of the individual effective resistances is determined by the necessary pilot arc current strengths that can be determined by the resistance values. After the pilot arc has been applied to the second electrode, preferably to the anode ^1, it opens the switching contacts of the ignition device and the igniter and thus switches both immediately after the ignition tion of the arc, and only the main arc circuit then remains in the operating state * 'After switching off the arc, the switching contacts of the ignitor and the ignition device are closed by the contactor ·

The puncture of the second variant of the invention deviates from the first as follows: After igniting the Pilotliehtbogens on the first auxiliary electrode and its ignition on the other auxiliary electrodes, the electrical potential of the first auxiliary electrode and then the remaining auxiliary electrodes from the potential of the second electrode _{9 is} preferably The potential of the anode, to which the respective potential determined by the series connection of all or ^{one of} the active resistances still active in the pilot circuit, is altered, is changed by the series circuit.

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Determination of the effective resistances determined and increases with progressive ignition Ms to a by the last effective resistance in front of the second electrode, preferably the anode, "determined value" The individual resistors and diodes must be dimensioned for this increasing towards the second electrode currents and the corresponding power loads be · ¹

The function of the third variant of the invention differs only slightly from the first as follows: The series connection of the individual diodes results in lower and equal spacings of the Kilfselektroden equal voltage loads, but in the direction of the switching contact increasing current loads ^ The ignition itself is the first Solution variant is similar

The function of the solution variant according to the invention with a capacitor connected to the first auxiliary electrode and a discharge resistor connected in parallel deviates from the previously described variants as follows. After the ignition device is switched on, an electrical breakdown occurs between the first electrode and the first auxiliary electrode © ¹ The electric potential The first auxiliary electrode, which was the same as the potential of the second electrode, preferably the anode, before breakdown, like that of the other auxiliary electrodes, is changed by the breakdown in the direction of the potential of the first electrode, thereby becoming larger at first, only at the second one Auxiliary electrode connected resistance of limited electrical current and high temporal change in current charging of the capacitor connected to the first auxiliary electrode and thus an equal Stromstärkevorläuf in Pilotiafbogen aufβ 'After the Err of a sufficiently high charging voltage at the capacitor and thus at the first auxiliary

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electrode and a caused by the outflowing plasma of the pilot arc sufficient ionization of the space between the first and second auxiliary electrode ignites the pilot arc to the second auxiliary electrode and extinguished at the first auxiliary electrode by the blocking effect of the connected charged capacitor «This capacitor is then on the in parallel relatively high-impedance discharge resistor on the dem arc in the Fehn the first auxiliary electrode corresponding electrical potential discharge * 'The further ignition of the pilot arc from the second auxiliary electrode to the other auxiliary electrodes and the second electrode as in the other solution variants « ^{1 of} the first of the first The auxiliary electrode connected capacitor has such a capacity that at the time of possible ignition of the pilot arc to the second auxiliary electrode, the required pilot arc current and the capacitor on the neces to achieve the same throughput voltage · '

The function of the Zündgerätanschlusses invention to an additional winding of a smoothing reactor is the following? After switching on the igniter whose ~ pulse voltage is transformed by inductive coupling via the additional winding or a part of a smoothing inductor in the arc main circuit and causes the electrical breakdown between the first electrode, preferably the cathode _s and the first auxiliary electrode * Then the pilot arc ignition occurs and the further ignition process as already described in the individual solution variants.

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- Embodiments

Based on embodiments, the subject of the invention will be explained in more detail »'In the accompanying drawings show

1 s pie first circuit variant of the ignition device with a series circuit of resistors and diodes on each auxiliary electrode;

51g _e ^; 2 s The second circuit variant of the ignition device with a series circuit of active resistors and auxiliary electrodes connected in between via diodes;

Pig * '3ί The third Scheitungsvariante the Zündvorrichtiing with a series circuit of diodes and connected in between via resistors connected ■ auxiliary electrodes;

IlgJ 4-i circuit of the ignition device with an inductive Zündinipuls feed and a capacitor at the first auxiliary electrode, as) Example of the third circuit variant illustrated «» ·

1 shows as a first embodiment the circuit of an ignition device in which at each auxiliary electrode Hg to H _n with the exception of the first auxiliary electrode H ^ a resistive RJ to R _n and a negative pole to the wählige auxiliary electrode H ^ Ms H _n connected diode D ₂ to D _{n is} connected in series with a surge protection device connected in parallel therewith in the form of a capacitor C ^ to the first auxiliary electrode H * only one effective resistance R ₁ and no diode is connected «, ¹ These individual series circuits are connected to those of the auxiliary electrodes H | to H _n ends facing away from parallel, the entire parallel circuit one another via a switching contact S * to the second electrode _9, the Eg _s is preferably connected as an anode connected »* The scarf

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ter S. is opened by a in the circuit of the arc L between the power source Q and this electrode Ea connected contactor Sch, when the arc current. flows between the two electrodes Ε, and Ep is the current source Q for the arc L, in the present example, a rectifier system connected, ¹ between the electrode E ^, which is preferably connected as Kat.is, and its adjacent first auxiliary electrode H an ignition device Z is connected to ignite the pilot arc P, in the present example a 100 Hz pulse ignitor, ¹ A switching circuit S2 mounted in the supply circuit of the ignition device Z is operated by the contactor Sch installed in the arc current circuit in the same way as the switching contact S. the actuated action resistors R .. to e _n are stepped in their ohm values so that the current of the pilot arc P while translating the next auxiliary electrode to H- EL increases or at least remains the same size, ¹

2 shows, as a second exemplary embodiment, the circuit of an ignition device in which, with the exception of the first auxiliary electrode H 1, a diode D ₂ Ms-D with a surge protection circuit in the form of a capacitor connected in parallel to it at each additional auxiliary electrode H ₂ to H _n G is turned on. ¹ positive pole side adjacent diodes D ₂ to D _{n are} each connected via a resistance Rp to R \ "'The first auxiliary electrode H, is only on a resistive R- to the positive pole side of the. to the second auxiliary electrode H ₂ connected diode D ₂ connected, "The positive pole terminal of the last preferably the anode next diode D _n is a real impedance TL · and connected in series with the switching contact S to the adjacent second electrode E _2, preferably to the anode, switched, 'The rest of the circuit corresponds to the first embodiment ,, ¹

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Fig. ' 3 shows, as a third exemplary embodiment, the circuit of an ignition device in which an effective resistance R to R _{n is} connected to each auxiliary electrode IL to H _n * ⁴ Zv / ischen the free, the auxiliary electrodes H ₁ to H opposite ends of each "adjacent effective resistors Ε ., Up to E is a diode D ^ to D- with a surge protection Beschnnng in the form of a capacitor C connected in parallel so switched that the negative poles of the diodes D '.. D to D- in the direction of the Hlotbogendurchzündfolge show, preferably from anode remote to anode-closer Auxiliary electrodes H- to H _n * "The second electrode E ₂ , preferably the anode, is connected to the active resistance R ¹ connected to the first auxiliary electrode JL via a switching contact S ₂ actuated by the contactor Sch ^1. The remainder of the circuit corresponds to the first exemplary embodiment ¹

FIG. 4 shows the circuit of an ignition device in which, between the first and second auxiliary electrodes H 1 and H _2, a capacitor C- is connected in parallel with a relatively high resistance R, which acts as a discharge resistor for the capacitor C- second electrode e ₂ leading Sclialtkontakt S- connected to the belonging to the second Hilfsele3rfcrode H ₂ effective resistance R ₂ 'Z ¥ / een the current source Q of the arc and the first electrode e, preferably the cathode is a choke coil Dr afc smoothing inductance for the Arc current connected "'This inductor Dr or on a part of it an additional winding for the transformation of the ignition pulses is mounted in the arc circuit''These are generated by the Z connected to the auxiliary winding igniter. ¹ The rest of the circuit corresponds to the third embodiment 'but it can also correspond to the first or second embodiment' ¹

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Claims (1)

- ¹⁵ - 227 1 13 Batentanspruch _e "arc igniter" fPlasittatrons and long arcs with relatively large electrode distances using HilfaäLektroden in the form of electrically conductive, against each other electrically iso-.lierten washers with central hole or Eingen or rods between two electrodes and connected to the auxiliary electrodes resistances and capacitive resistances and with a gas flow superimposed on the arc in the ignition direction, characterized in that each intermediate electrode (K.Υ.Υ.) without or with an equal or different number of interposed electrically powered, and not included in the ignition circuit (S ) or Neutroden ever a Wirkwiderstand (E ^. 'YR _n ) and, with the exception of the first, the one arc electrode (E ..), preferably the cathode, adjacent auxiliary electrode (H.), a negative pole to the auxiliary electrode (H ₂ .. 'H _n ) connected diode (D ₂ *' · '· ^), the egg ne overvoltage protection Beschalturig, for example in the form of a capacitor C is connected in parallel, in series and so for all auxiliary electrodes (H. "..Ή) obtained switching groups parallel to the other electrode (E ₂ ) of the arc (L) or Plasmatron ^ ·, preferably to the anode, via a switching contact (S ₁ ) are connected, of a in the main circuit of the arc ( L) is opened between the current source (Q) and the other electrode, preferably the anode, connected contactor (Sch) after reaching the nominal arc current and when the arc (L) is turned off, or that to each auxiliary electrode (H ^ y, H _n ) with the exception of the first, one Liehtbogenelektrode, preferably the cathode, adjacent auxiliary electrode (H ₁ ), one diode (D ₂ ^ YyD _n ) minus pole to the auxiliary - 16 - 7113 electrode (BLeVeEL) with one of the individual diode (DpAVD _n ) connected in parallel overvoltage protection circuit, for example in the form of a capacitor (C) and respectively adjacent diodes (DpAVD) pluspolseitig each with a resistance. (Rp · ΛE _n i) are interconnected, wherein the first auxiliary electrode (Hs) with only one active resistance (R-) connected to the positive terminal of the second auxiliary electrode (H ₂ ) associated diode (Dg), and between; the second electrode _(E?), preferably the Katod'3 _s and its adjacent last auxiliary _electrode; (H) an effective resistance (R _n ) is connected in series with a switching contact (S ..), which is connected to a contactor (Sch) in the manner already described, or that to each auxiliary electrode (H .., 'a Effective resistance (R .RTM.> VR _n ) is connected to the other end of which in each case between two adjacent effective resistors (R. AVR _n ) one diode each (D.VVD _n *) with a parallel-connected overvoltage protection circuit, for example in the form of a capacitor ( C) minus pole in the direction of the second and the further auxiliary electrodes (H-AVH _{n is} connected and between the at the first auxiliary electrode (H ..) connected effective resistance (R.) and the diode connected to it (D.) the one terminal and between the second electrode (E ₂ ), preferably the anode, and the power source (Q) of the other terminal of a switching contact (S.) is connected, which is already connected to a contactor (Sch), and that between the first n electrode (E.), preferably the cathode, and the next to her arranged auxiliary electrode (H.) a per se known ignitor (Z), z, 'BJ a 100 Hz »pulse ignitor, connected to the same Switching contact (S.) of the ignition device of the arc in the arc. contactor (Sch) after lighting the light , ^x - 17 - 22 71 13 arc (L) is switched off with a switching contact (S ₂ ) located in the igniter circuit, and that in the aforementioned variants instead of the Wirkwiderstand «state (E.) or an active resistance · diode combination (E, D) between the first Auxiliary electrode (H) and the second auxiliary electrode (H ₂ ) .a capacitor (C-) with a parallel to him relatively high-impedance discharge resistor (E _e ) is connected, and / or that in the aforementioned variants, the ignition device (Z) transformationally to a per se. Smoothing choke coil (Dr) or on a part of a smoothing choke coil (Dr) in arc »circuit between the first electrode (E-), preferably the cathode, and the power source (Q) is connected, which from the second auxiliary electrode (H ₂ ) remote end of the connected to her resistance (R ₂ ) via a switching contact (S) is connected in already mentioned circuit to the arc circuit, ;. ' Ignition device for arc plasmatrons and long arc according to claim 1, characterized in that the values of the active resistors (R - Y) connected to the individual auxiliary electrodes (R - VeiL) (R ^ Y ₆ R _n ) reduce the voltage drops of the arc (LP) between respectively adjacent auxiliary electrodes ( H ^ .YeH _n ) and between the second electrode (E ₂ ), preferably the anode _s and the auxiliary electrode connected to it (H, H ₂ , H _n ) are adapted so that the existing pilot arc (P) über'die individual auxiliary electrodes (H-.Y .H _n ) either equal or maximum possible electrical voltage differences between adjacent auxiliary electrodes (H ^. 'Y ¹ H _n ) or Rilfselektroden (H ^, H ₂ , H _n ) and electrodes (E-, E ₂ ) are present. ' -18 - 7 1 1 3 · ^! Ignition device for Lic hfbo genplasmatr ons and long arc according to claim 1, characterized in that between each auxiliary electrode (EL .ν »Ή) and the device connected to it, for example, effective resistance (R ₁ ^ YR _n ) or diode (D ₁ ^ VD _n ), one each of a connected in the arc circuit NEN sound insulation (Sch) or of. a switching contacts (S..eV «S) to be actuated in chronological order of the switching off of the individual auxiliary electrodes, in particular after the pilot arc (P) has been transmitted to the next auxiliary electrode (H ₂ VeVH _n ) or the second electrode (Ε") previously operated auxiliary electrode current circuits interrupting, is connected. ¹ - 19 -