Electrode device

Abstract

In the case of the improved instrument (10), the electrode (20, 20') is equipped with a heat dissipation device (28, 28') in the form of a single-layer or multi-layer coating (29, 29'), (30). The coating preferably has a higher electrical conductivity and a higher thermal conductivity than the material of the electrode base body (27, 27'). The coating also preferably has a lower melting temperature than the material of the electrode base body (27). The melting temperature TÜ of the coating is preferably below (1100° C.). If the coating (29, 29', 30) is multi-layered, the melting temperature TO of the outer surface layer (38) is preferably also below (1100° C.), further preferably below (1000° C.).

Description

Technical Field

[0001] The invention relates to an electrode device for an electrosurgical instrument, in particular an instrument for plasma coagulation of biological tissue. Background Art

[0002] Tissue coagulation devices are known from various publications and from practice. For this purpose, see DE 102011116678A1 and DE 69928370 T2. Both publications disclose devices with electrodes, which are designed, for example, in annular form and can be made of a suitable material, such as tungsten in particular, which is distinguished by its thermal stability.

[0003] In addition, a plasma coagulation instrument with a hose-shaped instrument body is known from DE 10030111 A1, in which a hexagonal electrode made of metal is arranged in the lumen of the hose-shaped instrument body. The electrode is connected to a feeder so that an HF voltage can be supplied to the electrode arranged at the far end of the hose. A discharge is formed at the tip at the far end of the plate-shaped electrode, thereby generating a plasma stream, in particular an inert gas plasma stream. The airflow around the electrode simultaneously radiates heat from the electrode, thereby aiming to avoid excessive heating of the electrode. By heat dissipation, it is also intended to minimize the melting loss characteristics at the discharge portion of the electrode and thereby increase the service life of the instrument.

[0004] However, efficient cooling of the electrode plates by gas flow requires high gas flow rates, which is not always desirable.

[0005] It is also known from WO 2005 / 046495 A1 to use an ignition electrode made of a tungsten wire, the end of which is placed at the distal end of an otherwise hose-like or tubular instrument body. The tungsten wire arranged in the lumen of the body is fixed thereto by the tungsten wire and a plate for cooling the tungsten wire is held at a certain distance from the distal end of the body. However, the heat dissipation of the tungsten wire is impeded by the transition between the plate and the tungsten wire.

[0006] Due to the melting of the electrode, particles, in particular metal particles, can enter the spark and / or plasma jet and thus ultimately enter the living tissue, which is increasingly rejected. Summary of the invention

[0007] It is therefore an object of the present invention to specify a design which can be used to reduce material erosion during use of an electrosurgical instrument, in particular a plasma surgical instrument.

[0008] This object is achieved with the electrode arrangement according to the invention and with the device according to the invention:

[0009] The electrode arrangement according to the invention comprises an electrode on which a distally directed tip is formed. The cross section of the electrode increases continuously or by at least one level in the proximal direction away from the tip. The electrode is made of a material combination, the thermal conductivity of which is preferably greater than 20 W / (m*K), whereby a greatly reduced electrode loss can be achieved. The electrode is provided with a thermally conductive coating, whereby the service life of the electrode is increased and the service life of an instrument equipped with the electrode is also increased. The thermally conductive coating leads to an increase in the service life of the electrode relative to the same electrode without the coating, regardless of the thermal conductivity of the electrode. The coating preferably extends in the distal direction up to the vicinity of the distal end of the electrode or covers the distal end of the electrode.

[0010] Starting from the distal tip, the electrode cross section can be increased step by step or continuously until the electrode contacts the wall of the lumen in which the electrode is arranged. If the cross-sectional increase from the tip to the proximal part of the electrode is carried out step by step, one or more levels can be set for this purpose. The tip of the electrode (and the edge area of ​​the electrode adjacent to the tip) is the place where sparks or plasma flows are usually emitted. Therefore, the tip and the part of the electrode adjacent to the tip form the position where the discharge base point of the discharge is located. Current concentration occurs at this base point, which simultaneously forms a heat source. At the discharge base point, the electrode can be exposed, that is, the coating may not exist or has been removed during operation. Through two measures, namely, the cross section of the electrode increases in the proximal direction and by combining the material whose thermal conductivity is preferably greater than 20W / (m*K) for the electrode, the heat formed at the electrode base point is dissipated much more effectively than before when using the same structural form of the electrode made of stainless steel or chrome-nickel steel. The electrode according to the invention is therefore distinguished in particular in that its thermal conductivity, measured from the tip in the proximal direction and / or transversely to the proximal direction, is greater than the thermal conductivity of stainless steel.

[0011] Preferably, the electrode has a portion extending at least 2.5 mm in the proximal direction from its tip, the heat capacity of which is less than 4.17 mJ / K. This facilitates rapid local heating of a small space (e.g. limited to a few square millimeters) of the electrode tip and helps fix the discharge base point in this area. In this way, the coating can be melted regionally, for example in a small area near the distal tip.

[0012] The combination of an electrode geometry in which the electrode cross section increases in the proximal direction away from the tip enables the use of a tip with a particularly small fillet radius, which can in particular be less than 1 / 10 of the largest transverse dimension of the electrode, wherein the electrode is formed from a combination of highly thermally conductive materials. This results in high field strengths at the electrode tip, which can lead to the formation of sparks and plasma even at low HF voltages and currents. The electrode is then particularly easy to ignite.

[0013] Preferably, the electrode is designed in the form of a plate, wherein the increase in the cross section of the electrode is achieved by a transverse dimension of the electrode which increases in the axial direction in the proximal direction away from the tip. This transverse dimension can be increased continuously, thereby achieving particularly good heat dissipation. A continuous increase in the cross section and transverse dimension can be achieved by a steplessly formed edge connected to the tip of the electrode.

[0014] The electrode can be configured as a plate having two flat sides connected to each other by a narrow side. Two edges extending toward each other can meet at a tip, which forms the distal end of the electrode. An edge can be formed between the narrow side and the flat side. Such an electrode can be provided, for example, as a plate blank.

[0015] The electrode can also be configured as a wire electrode, thus as a thin rod, the distal end of which forms a tip. The wire (needle, thin rod) can be connected to a holder which extends radially through the lumen of the probe and is part of the electrode.

[0016] According to the invention, the electrode is made of a material combination, which is formed in the following way: the electrode is made of a substrate, which has at least one surface, on which a heat sink is mounted. In this case, the heat sink preferably extends in the distal direction up to the tip of the electrode, at least up to the area occupied by the discharge base point during operation. Therefore, the heat generated there can be transferred directly to the heat sink without heat transfer from the electrode to the heat sink. In other words, the heat sink is in direct contact with the heat source in the form of the discharge base point. The heat sink preferably extends in the proximal direction at least into the area of ​​the electrode in which the electrode has its largest transverse dimension.

[0017] For this purpose, in the simplest case, the electrode is made of a substrate, and a heat-conducting coating, for example, a heat-conducting coating in the form of a heat-conducting coating is applied to the substrate as a heat sink. The layer preferably extends to the tip of the electrode and extends over most of the flat side of the electrode or over the entire flat side of the electrode. The coating can also extend on the narrow side of the electrode. If the electrode is formed, for example, by stainless steel or other materials with poor thermal conductivity, the heat sink is formed by a material with particularly good thermal conductivity, such as silver, diamond-like carbon (DLC), etc. However, preferably, the heat sink is formed by a metal material, which is also conductive, so that, for example, a heat sink in the form of a heat dissipation layer helps to conduct current and can be in direct contact with the discharge base point. The heat sink can also be made of a ceramic material with good thermal conductivity, such as AlN (aluminum nitride). Ceramic materials can be constructed to be conductive or electrically insulating. Preferably, a heat sink configured as a heat-conducting coating is also particularly conductive. It is particularly advantageous that the conductivity of the coating is greater than the conductivity of the substrate. Preferably, the layer is at least partially made of silver. It can be pure silver or a silver alloy or a multilayer structure, in which at least one layer, preferably the layer located on the surface, is made of silver or a silver alloy.

[0018] The layer structure may include a layer that affects adhesion, such as an intermediate layer arranged between the layer near the surface and the substrate. The intermediate layer may in particular be a layer that affects the adhesion of the layer near the surface on the substrate. The intermediate layer may in particular be an adhesive layer that is conducive to coating the substrate (stainless steel) with a coating material (silver). During operation, the adhesive layer may promote redistribution of the coating material away from the distal tip.

[0019] Preferably, the melting temperature of the surface material is lower than the melting temperature of the substrate. If an intermediate layer is present, the melting temperature of the intermediate layer is lower than the melting temperature of the substrate and higher than or as high as the melting temperature of the material of the surface layer. However, the melting temperature of the intermediate layer may also be lower than the melting temperature of the coating material.

[0020] Further preferably, the thermal conductivity of the material of the surface layer is higher than the thermal conductivity of the substrate. If an intermediate layer is present, the thermal conductivity of the material of the intermediate layer is preferably higher than the thermal conductivity of the substrate and lower, higher or equal to the thermal conductivity of the material of the surface layer.

[0021] Therefore, in a particularly preferred embodiment, the heat sink has an electrical conductivity and in particular also a thermal conductivity which is respectively greater than the electrical conductivity and thermal conductivity of the material of the substrate.

[0022] In particular, alloys containing iron and / or chromium and / or nickel are suitable as substrates. Carbon and / or manganese and / or phosphorus and / or sulfur and / or silicon and / or nickel and / or nitrogen and / or molybdenum may also be present as further alloying components. Stainless steel preferably used as substrate has the following composition:

[0023]

[0024] In particular, gold or nickel or alloys thereof are suitable as materials for the intermediate layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Embodiments of the present invention are illustrated in the accompanying drawings.

[0026] Figure 1 An apparatus according to the invention, the associated feed device and the neutral electrode are shown in a very schematic partial perspective view;

[0027] Figure 2 A schematic perspective longitudinal section is shown according to Figure 1 The distal end of the instrument;

[0028] Figure 3 The side view shows the Figure 2 The electrodes of the instrument;

[0029] Figure 4 , Figure 5 and Figure 6 Shown according to Figure 3 Different cross sections of electrodes;

[0030] Figure 7 The schematic cross-sectional view during operation shows the Figures 2 to 6 Instruments;

[0031] Figure 8 Shown in accordance with Figure 2 A modified embodiment of an electrode of the apparatus;

[0032] Fig. 9 and Fig.10 Shown in accordance with Figure 2 Another embodiment of an electrode of an apparatus. DETAILED DESCRIPTION

[0033] exist Figure 1 1 and 2 illustrate an apparatus 10 for plasma-assisted tissue treatment. Tissue treatment may include ablation, coagulation, cutting or other treatment methods.

[0034] The instrument 10 is connected to an apparatus 11, which comprises a gas source 12, for example an argon source, and a generator 13 for feeding the instrument 10. The gas source is connected via corresponding connection means to a pipeline 14, which leads to the instrument 10 and is inserted into a pipeline 15, through which the gas is fed to the instrument 10. The generator 13 is also connected via corresponding connection means to a neutral electrode 16, which is mounted on the patient before using the instrument 10. However, the following description also applies to instruments with other neutral electrode configurations.

[0035] The instrument 10 has a distal end 17 which is Figure 2 As can be seen, the instrument 10 comprises a tube or hose 18 which encloses a lumen 19 which is open at the distal end 17 of the hose 18. In the region of the distal end 17, the hose 18 can be provided with an internal or external reinforcement, for example in the form of a ceramic sleeve, which Figure 2 The hose 18 can thus be constructed in one or more layers. An example of an instrument that is inserted into the open end of the hose 18 is known from WO 2005 / 046495 A1.

[0036] An electrode 20 is arranged in lumen 19 and is electrically connected to a wire 21 belonging to line 14 and extending through lumen 19. Wire 21 can be welded to electrode 20 or can also be mechanically connected thereto, for example by crimping.

[0037] The electrode 20 preferably has Figure 3 The electrode 20 has a sharp or perhaps slightly rounded tip 22 at its distal end, the tip having a fillet radius R ( Figure 2 ) is as small as possible and preferably less than one tenth of the transverse dimension q, which should be measured transversely to the axial direction and coincide as closely as possible with the inner diameter of the lumen 19. The electrode 20 is preferably configured in a plate-like manner, that is, the thickness of the electrode is much smaller than the transverse dimension q of the electrode. This is, for example, Figure 4 It is found that the figure shows the electrode 20 in Figure 3 The cross section at the dotted section line IV-IV has a thickness d that is less than 1 / 5 of the transverse dimension q, preferably less than 1 / 10 of the transverse dimension q.

[0038] As from Figure 4 As can be further seen in FIG. 2 , the electrode 20 has two flat sides 23, 24, which are connected by narrow sides 25, 26. As a result, an overall quadrilateral, preferably rectangular, cross section Q is obtained, which is bounded by the flat sides 23, 24 and the narrow sides 25, 26. The quadrilateral cross section can also be bent once or multiple times, for example in an S-shape.

[0039] The electrode 20 has a conical region at its distal end, in which the narrow sides 25, 26, which otherwise run parallel to one another, are arranged to converge toward the tip 22. Figure 3 As shown, the parts of the narrow sides 25, 26 that run converging to each other can be designed to be straight or also convex or concave. These parts define an angle preferably in the range of 20° to 100° with respect to each other.

[0040] As in Figure 5 and Figure 6 As shown in the sections VV and VI-VI shown separately in FIG, the cross section of the electrode 20 decreases in the distal direction D toward the tip 22 or in other words increases in the proximal direction P. Figure 5 and Figure 6 As shown, the thickness d of the electrode 20 in the tapered region towards the tip 22 may remain constant. However, the thickness d may also decrease towards the tip 22. However, in any case, the lateral dimension Q in the tapered region towards the tip 22 decreases.

[0041] In a preferred embodiment of the present invention, the electrode 20 has a multi-layer structure, such as Figure 4 , Figure 5 and Figure 6 For this purpose, the electrode 20 has an electrode substrate 27, which is connected to a heat sink 28 at least on its flat sides 23, 24, but optionally also on its narrow sides 25, 26. In the current embodiment, the heat sink is made of a full-surface coating of the flat side of the electrode substrate 27 with a heat-conducting coating 29, 30. In this embodiment, the substrate 27 can be made of stainless steel, while the coatings 29, 30 are made of other materials with better thermal and / or electrical conductivity. Silver has been shown to be particularly suitable for this. Possible other coatings are made of aluminum and / or copper and / or hard metal and / or DLC and / or tungsten and / or layers, for example metal layers with CBN (cubic boron nitride) embedded therein, diamond powder or similar materials with good thermal conductivity.

[0042] The apparatus described in this connection operates as follows:

[0043] like Figure 7As explained in , during operation, a gas flow 31 from a gas source 12 flows through the lumen 19 of the instrument 10. This gas flow (preferably an argon gas flow) blows along the two flat sides 23, 24 of the electrode 20. At the same time, a high-frequency current is fed to the electrode 20 via the line 21. Here, the operating frequency of the generator 13 and therefore the frequency of the current is preferably above 100 kHz, preferably above 300 kHz, and further preferably above 500 kHz. The current leaves the electrode 20 at the tip 22 and the adjacent region of the tip and forms a spark that jumps to the biological tissue of the patient, which is not further explained, or a plasma 32 that flows thereto. Here, the base point 33 of the spark or plasma contacts the narrow sides 25, 26, but in particular the flat sides 23, 24 of the electrode 20, wherein the base point region 33 occupies, for example, less than 1 / 10 of the axial length (to be measured in the proximal direction) of the region of the electrode 20 in which the narrow sides 25, 26 diverge away from the tip 22. The coating 29, 30 can extend into this region and preferably extends to the tip 22. By this, the spark or plasma jet is fed directly by the coating 29, 30. The thickness of the coating 29, 30 can be relatively small. It has been shown that a coating with a thickness of 10 to 20 μm already leads to a significant extension of the service life of the electrode 20 and to a significantly reduced material galvanic corrosion and a significantly reduced heat radiation of the electrode. Preferably, the thickness of the coating, for example made of silver, is 20 μm, 30 μm or 50 μm. Preferably, the coating has a thermal conductivity value of more than 400 W / (m*K). The thickness of the electrode can be, for example, 0.1 mm. The thermal conductivity value of the entire electrode is also preferably more than 400 W / (m*K). As a result, the electrode 20 made of the material combination of stainless steel / silver has an excellent service life.

[0044] In a modified embodiment, the electrode cross section may also increase in the proximal direction not continuously as in the above-described embodiment, but in abrupt steps, that is, in one or more stages. Figure 8 However, this embodiment also realizes the design according to the present invention, so when describing this electrode 20 ', refer to the embodiment according to the present invention. Figures 1 to 7 The description of the embodiments of the invention is continued. The reference numerals already introduced are continued, wherein these reference numerals are respectively provided with a prime for differentiation. Except for the following particularities, the above description applies correspondingly to the embodiments according to Figure 8 implementation method.

[0045] The electrode 20' has a tip 22', which can be formed by the tip or blunt end of a linear, straight or wavy electrode portion. The linear electrode portion 34 includes a core 35, which forms a substrate 27' and can be configured as a thin cylindrical pin. The diameter of the linear electrode portion is preferably less than 0.5 mm and is, for example, 0.3 mm. The core 35 is provided with a coating 29', which forms a heat sink 28' in combination with an electrode holding plate 36 when necessary. The electrode portion 34 can be connected to the electrode holding plate 36 by welding, pressing or otherwise. A material-matched connection is preferred due to better heat transfer. The electrode holding portion 36 can be made of stainless steel or other materials, which are provided with a thermally conductive coating such as tungsten, copper, aluminum, DLC, etc., or which are formed of a thermally conductive material such as tungsten, copper, aluminum, DLC, etc. At the transition position from the linear electrode portion to the electrode holding plate 36, the cross-section of the electrode increases in a jumpy manner.

[0046] The electrode 20 may also be Fig. 9 and Fig.10 The cross section is designed to have circular sections with different diameters at axial distances.

[0047] In the case of all electrodes 20, 20', regardless of the geometry and regardless of whether the electrode cross section increases continuously or stepwise in the proximal direction or whether it remains constant or decreases locally, the coating 29, 29', 30 significantly increases the service life of the electrode 20, 20' and the instrument 10. It is particularly advantageous here if the coating 29, 29', 30 extends at least about 5 mm to 10 mm or about 10 to 20 mm in the proximal direction from the tip 22. Preferably, the coating 29, 29', 30 is made of a metal, for example silver, which has a melting temperature T ü Lower than the melting point T of the base material, such as stainless steel G The coatings 29, 29', 30 preferably also have a thermal conductivity λ ü , which is higher than the thermal conductivity λ of the substrate G .

[0048] The coating 29, 29', 30 can also be made of an intermediate layer 37 which is in direct contact with the substrate 27 and affects adhesion, and a surface layer 38 arranged on the intermediate layer 37. The surface layer 38 is preferably made of a metal having a melting temperature T O Lower than the melting temperature T of the middle layer Z or roughly the melting temperature T of the middle layer Z The melting temperature of the intermediate layer is lower than the melting temperature T of the material of the electrode base body 27. G The surface layer 38 is also preferably made of a material having a thermal conductivity λ O The thermal conductivity λ of the intermediate layer 37Z The thermal conductivity λ of the intermediate layer 37 is at least as high as Z Preferably higher than the thermal conductivity λ of the material of the electrode base body 27 G .

[0049] In all the previously described electrodes 20 , 20 ′, it also applies that the cross-sectional area A of the coating 29 , 29 ′, 30 ü At least at the tip 22 (up to about 2.5 mm in the proximal direction) the electrode base body has a cross-sectional area A G The electrode 20, 20' also has a portion extending at least 2.5 mm in the proximal direction from its tip 22, the heat capacity of which is less than 4.17 mJ / K. The electrode 20, 20' has a volume V E , which volume is preferably equal to the surface dimension A of the coating 29, 29', 30 üO Preferably, the surface size A üO With volume V E The ratio is greater than 2.24mm -1 .

[0050] Based on Figure 8 , Fig. 9 or Fig.10 When the instrument 10 with the electrode 20' of the embodiment of the present invention is operated, the discharge is firstly carried out from the tip 22 and then from at least a part of the linear electrode part 34 and the spark or plasma stream formed is thus emitted. The conductive and thermally conductive coating 29', which is preferably a silver coating, significantly reduces the resistance of the electrode 20 or 20'. The high-frequency alternating current of the generator 13 is concentrated in the outer layer of the electrode 20, 20' and thus flows substantially through the coating 29, 30, 29'. Thereby, the ohmic loss at the electrode 20, 20' is minimized, and the heat reduced by the coating is also significantly better conducted away from the discharge foot and distributed so that the heat can be transferred over a large area on the air flow. The surface layer 38 and possibly also the intermediate layer 27 can melt and retract slightly from the tip 22 in the proximal direction. The discharge base point 33 remains stationary at the tip 22 (and the area immediately adjacent to the tip, approximately 2.5 mm). This reduces the thermal load of the electrode 20, 20' and the instrument 10.

[0051] In the case of the improved instrument 10, the electrodes 20, 20' are provided with heat dissipation means 28, 28' in the form of a single or multi-layer coating 29, 29', 30. The coating preferably has a higher electrical conductivity and a higher thermal conductivity relative to the material of the electrode base body 27, 27'. The coating also preferably has a lower melting temperature than the material of the electrode base body 27. The melting temperature T of the coating is üPreferably below 1100° C. If the coating 29 , 29 ′, 30 is multi-layered, the melting temperature T of the outer surface layer 38 is O It is also preferably below 1100°C, further preferably below 1000°C.

[0052] Reference numerals:

[0053] 10 Instruments

[0054] 11 Equipment

[0055] 12 Air source

[0056] 13. Generator

[0057] 14 Pipelines (for flow)

[0058] 15 Pipeline (for gas)

[0059] 16 Neutral electrode

[0060] 17 The distal end of the instrument 10

[0061] 18 Hose

[0062] 19 Lumen

[0063] 20 Electrodes

[0064] 21 lines

[0065] 22 Tip

[0066] q Transverse dimension of electrode 20

[0067] d Thickness of electrode 20

[0068] 23, 24 Flat side of electrode 20

[0069] 25, 26 Narrow side of electrode 20

[0070] Cross section of Q electrode 20

[0071] α Angle between the parts of the narrow sides 25, 26

[0072] D Distal direction

[0073] P Proximal direction

[0074] λ Thermal conductivity

[0075] λ ü Thermal conductivity of coatings 29, 29', 30

[0076] λ Z Thermal conductivity of the intermediate layer 37

[0077] λ GThermal conductivity of the substrate 27

[0078] λ O Thermal conductivity of the surface layer 38

[0079] 27 Electrode substrate

[0080] 28 Heat sink

[0081] 29, 29', 30 coating

[0082] 31 Airflow

[0083] 32 Plasma

[0084] 33 basis points

[0085] 34 Linear electrode part

[0086] 35 Core

[0087] 36 Electrode holding part

[0088] 37 Middle Layer

[0089] 38 Surface layer

[0090] T ü Melting temperature of coatings 29, 29', 30

[0091] T G Melting temperature of the material of the electrode substrate 27

[0092] T O Melting temperature of the surface layer 38

[0093] T Z The melting temperature of the intermediate layer 37 .

Claims

1. An electrode (20, 20') for an electrosurgical instrument (10) for plasma coagulation, wherein the electrode (20, 20') has a distally directed tip (22), the electrode (20, 20') being configured such that the electrode cross section (Q) increases continuously or by at least one level in a proximal direction (P) from the tip, It is characterized in that The electrodes (20, 20') are made of a material combination having a thermal conductivity (λ) greater than 20 W / (m*K), and The electrode (20, 20') is made of an electrode substrate (27) having a heat conductive coating (29, 29', 30). The coating (29, 29', 30) is made of an intermediate layer (37) arranged in direct contact with the electrode substrate (27) and a surface layer (38) arranged on the intermediate layer (37). The surface layer (38) is made of metal or metal alloy, and the thermal conductivity of the metal alloy is D Higher than the thermal conductivity λ of the intermediate layer (37) Z , the thermal conductivity of the intermediate layer in turn being higher than the thermal conductivity λG of the material of the electrode main body.

2. The electrode according to claim 1, characterized in that The electrode (20, 20') has a maximum transverse dimension (q) and has a fillet radius (R) at its tip (22), which is less than one tenth of the maximum transverse dimension (q).

3. An electrode according to any one of the preceding claims, characterized in that The electrode (20, 20') is designed as a wire or as a plate having two flat sides (23, 24) which are connected to one another via narrow sides (25, 26).

4. The electrode according to claim 3, characterized in that The electrode (20, 20') has at least one flat side (23, 24), and the heat-conducting coating (29, 29', 30) is formed by a layer that occupies the entire flat side (23, 24).

5. The electrode according to claim 1 or 2, characterized in that: The coating (29, 29', 30) is constructed of a heat-conducting material and has electrical and / or thermal conductivity greater than that of the base body (27, 27').

6. The electrode according to claim 5, characterized in that The thermally conductive material is a metal or a metal alloy.

7. The electrode according to claim 1 or 2, characterized in that: The coating (29, 29', 30) is formed and arranged to extend into a region (33) provided for direct contact with a spark emitted from the electrode (20, 20').

8. The electrode according to claim 1 or 2, characterized in that: The coating (29, 29', 30) is made of metal or metal alloy, and the melting temperature of the metal alloy is ü Lower than the melting temperature T of the material of the electrode substrate (27) G .

9. The electrode according to claim 1, characterized in that The surface layer (38) is made of metal or metal alloy, the melting point of the metal alloy is O Lower than the melting temperature T of the intermediate layer (37) Z The melting temperature of the intermediate layer is lower than the melting temperature T of the material of the electrode substrate (27). G .

10. The electrode according to claim 1 or 2, characterized in that: The coating (29, 29', 30) has a cross-sectional area A ü , and the material of the electrode substrate (27) has a cross-sectional area A G , where the cross-sectional area A ü With the cross-sectional area A G The ratio is greater than 0.

12.

11. The electrode according to claim 1 or 2, characterized in that: The electrode (20, 20') has a portion extending at least 2.5 mm in the proximal direction from its tip (22), wherein the heat capacity of the portion is less than 4.17 mJ / K.

12. The electrode according to claim 1 or 2, characterized in that: The electrode (20, 20') has a volume V E , and the coating (29, 29', 30) has a surface dimension A üO , wherein the surface dimension A üO With the volume V E The ratio is greater than 2.24mm -1 .

13. An apparatus (10) comprising an electrode (20, 20') according to any one of the preceding claims.

14. The apparatus (10) according to claim 13, characterized in that The device comprises a tube or hose (18) which surrounds a lumen (19) which is open at a distal end (17) of the tube or hose (18) and which can be connected to a gas source, wherein the electrodes (20, 20') are arranged completely or partially in the lumen (19) and can be connected to a generator (13).

15. The apparatus (10) according to claim 14, characterized in that The gas source is an argon gas source.

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