High voltage pulse generator, method of operating high voltage pulse generator

Abstract

The invention relates to a Marx generator comprising a circuit comprising at least two capacitors arranged to be charged in parallel and discharged in series. The circuit comprises at least two spark gap switches, where each spark gap switch comprises two electrodes separated by a gap distance filled with a pressurized gas, each spark gap switch is configured to allow an electric spark to pass between two electrodes of the spark gap switch in the event that a potential difference between the two electrodes exceeds a breakdown voltage, and wherein the Marx generator comprises a regulating unit, and an adjustment unit configured to adjust a gap distance between two electrodes of each of the at least two spark gap switches in order to control the output voltage, where the adjustment unit is configured to adjust the gap distance by means of a voltage-controlled actuator and / or a capacitance-controlled actuator.

Description

Technical Field

[0001] This invention relates to a high-voltage Marx generator. Furthermore, this invention relates to a method of operating a high-voltage Marx generator. Additionally, this invention relates to a controller or control system for a high-voltage Marx generator, and a computer program product. Furthermore, this invention relates to a spark gap device for a Marx generator. Furthermore, this invention relates to a triggering / ignition mechanism for a Marx generator. Furthermore, this invention relates to a system including a Marx generator, such as an electrical pulse drilling system. Background Technology

[0002] A Marx generator is a circuit used to generate high-voltage pulses. This type of high-voltage pulse generator has a specific circuit topology and is widely used in a variety of applications. Typically, a Marx generator consists of multiple stages (see circuit branches), each stage comprising an energy storage capacitor and a switch. The capacitor is charged in parallel with a charging voltage and then discharged in series through the switch, generating a high-voltage pulse. During discharge, the generator can deliver its energy to a load that can be resistive, inductive, and / or capacitive. A Marx generator is configured to generate high-voltage pulses with a voltage greater than its supply voltage.

[0003] Typically, a Marx generator comprises multiple capacitor stages. The spark gaps in each stage can operate in self-breakdown mode. In addition to the output spark gap, each spark gap is connected to two charging branches, each connected to one of the two terminals of the spark gap. Therefore, a total of 2(N-1) charging branches are associated with an n-stage Marx generator. When the charging voltage of each capacitor stage at the Marx generator output is U, a voltage pulse with a peak value of n*U can be obtained upon breakdown. For example, a 100-stage Marx generator, each charged to 10kV, can generate approximately 1000 kV at the load. Similarly, a 10-stage Marx generator, each charged to 100kV, will generate approximately the same voltage at the load.

[0004] The switch in a Marx generator is typically a gas-insulated spark gap consisting of two main electrodes. The Marx generator may include a housing containing a predominantly gaseous atmosphere. Multiple capacitor stages may be arranged within the housing.

[0005] High-voltage Marx generators have many potential applications, such as electro-pulse drilling. In electro-pulse drilling, an electric arc generated by a Marx generator can be used to drill through rock formations. However, the surfaces to be drilled (e.g., rock formations) often have non-uniform material properties, which can lead to ineffective drilling.

[0006] Better control over the output of the Marx generator is required. Robust and accurate execution of this control is desired, even when the Marx generator is located in a remote location (e.g., an electric pulse drill bit). Additionally or alternatively, it is generally desirable to select the Marx generator's output based on the input power supply. Summary of the Invention

[0007] One object of the present invention is to provide a method and system for eliminating at least one of the above-mentioned disadvantages.

[0008] Additionally or alternatively, one object of the present invention is to improve the operation of the Marx generator.

[0009] Additionally or alternatively, an object of the present invention is to provide a Marx generator with improved (voltage) output flexibility.

[0010] Additionally or alternatively, one object of the present invention is to improve the control of the output of the Marx generator.

[0011] Additionally or alternatively, an object of the present invention is to control the output of the Marx generator within a predetermined range at predetermined time points in an efficient and robust manner.

[0012] Additionally or alternatively, one object of the present invention is to improve the self-breakdown of the spark gap in a Marx generator.

[0013] Additionally or alternatively, an object of the present invention is to prevent overvoltage and / or undervoltage breakdown of one or more spark gaps in a Marx generator.

[0014] Additionally or alternatively, an object of the present invention is to reduce losses caused by overvoltage breakdown of one or more spark gaps.

[0015] Furthermore, the present invention provides a Marx generator comprising a circuit including at least two capacitors arranged to charge in parallel and discharge in series, wherein, during discharge, an output voltage is generated by summing the charging voltages of each of the at least two capacitors, wherein the circuit includes at least two spark gap switches, wherein each spark gap switch includes two electrodes separated by a gap distance, the space between the two electrodes being filled with pressurized gas, and wherein each spark gap switch is configured to allow an electric spark to pass between the two electrodes if the potential difference between the two electrodes of the spark gap switch exceeds a breakdown voltage, and wherein the Marx generator includes an adjustment unit configured to adjust the gap distance between the two electrodes of each of the at least two spark gap switches to control the output voltage, wherein the adjustment unit is configured to adjust the gap distance by means of a voltage-controlled actuator and / or a capacitive actuator.

[0016] The Marx generator is configured to actively adjust / set the electrode gap distance of the spark gap switch via pressure and / or controlled-capacitance actuators. This active control of the gap distance allows for robust and precise control of the Marx generator's output. Using a controlled-pressure / controlled-capacitance actuator to mechanically adjust the relative distance between the electrode pairs of the spark gap switch in the Marx generator offers significant advantages over directly adjusting the pressure in the spark gap switch. Pressure / capacitance actuators provide greater adjustment flexibility for the Marx generator's output while maintaining favorable reliability and accuracy. The robust design of controlled-pressure / controlled-capacitance actuators allows for use with Marx generators even under harsh conditions. The output voltage of the Marx generator can be remotely operated, maintained, set, and / or adjusted more effectively. Furthermore, pressure / capacitance actuators can operate without electronic components, allowing for reliable operation near the spark gap switch.

[0017] Optionally, the adjustment unit includes at least one of a pressure control module or a volume control module, wherein the pressure control module is configured to operate the pressure-controlled actuator to manipulate the fluid actuation pressure to adjust the gap distance, and wherein the volume control module is configured to operate the volume-controlled actuator to manipulate the actuation volume of the medium to adjust the gap distance.

[0018] Pressure-controlled actuators manipulate fluid pressure for actuation, and / or volumetric actuators manipulate the volume of the medium for actuation. Even when the Marx generator is located remotely, such as when it is positioned at an electric pulse drill bit, the output can still be effectively set and / or regulated. Pressure / volume actuators can be coupled to one or more fluid lines. For example, pressure-controlled actuators can be pneumatically operated, and / or volumetric actuators can be hydraulically operated.

[0019] Pressure-controlled actuators are configured to provide actuation (e.g., force, surface displacement, rotation, etc.) using a pressure-controlled fluid (e.g., gas). While changes in fluid volume can be caused by the actuator as a result of changes in fluid pressure, control is performed based on pressure rather than volume. Employing fluid pressure actuators allows for inexpensive and robust designs that provide precise control over the gap distance between electrodes.

[0020] Capacitive actuators are configured to provide actuation (e.g., force, surface displacement, rotation, etc.) using a volume-controlled medium (e.g., a liquid). Although pressure changes in the medium can be caused by the actuator as a result of changes in the medium's volume, capacitive actuators can provide highly precise control. For example, a capacitive actuator can be configured to increase the volume of the medium by means of a pump when the gap distance needs to be reduced. Therefore, actuation can be performed based on volume changes (i.e., the volume of medium added / removed). Although this control may result in pressure changes in the medium (e.g., incompressible hydraulic fluids), the volume of the medium is actively / directly controlled.

[0021] In some examples, a controlled-capacity actuator may include a piston for displacing a volume of medium (such as hydraulic fluid, e.g., oil). In some examples, a biasing member, such as a spring, may be used to push the piston to a biased position. However, other arrangements may also be used; for example, the controlled-capacity actuator may include various types of pumps configured to perform actuation accurately based on volume. For this purpose, data indicating the volume can be actively tracked and controlled.

[0022] Optionally, the adjustment unit includes an adjustment member configured to move one of the two electrodes of the at least one spark gap switch relative to the other of the two electrodes of the at least one spark gap switch.

[0023] Mechanically transmitting actuation from a pressure-controlled actuator and / or a capacitive actuator to one or more electrodes for adjusting the gap distance can be achieved in various ways. The adjusting member can be coupled to one of the two electrodes in the electrode pair of the pressure / volume actuator and the spark gap switch. The connection between the electrodes of the pressure / volume actuator and the spark gap switch can be direct or indirect. For example, a beam or rigid rod can be used to transmit linear motion. However, one or more rotating members can also be used. In some examples, the adjusting unit has multiple moving parts. Various mechanical arrangements are envisioned.

[0024] Optionally, the adjusting member is arranged to mechanically connect a subset of electrodes of the pressure / volume actuator and the spark gap switch, such as to allow adjustment of the relative electrode pair gap distance by means of the pressure / volume actuator. One or more pressure / volume actuators may be used.

[0025] In some examples, the adjustment unit includes a lever unit. The lever unit may include a beam or rigid rod pivoting at a fixed hinge (see fulcrum). The lever unit can be used to amplify the input force provided by a pressure-controlled actuator and / or a capacitive actuator to provide a greater output force. In this way, precise adjustment of the clearance distance can be achieved.

[0026] Optionally, the adjusting member is arranged such that one of the two electrodes of each spark gap switch moves together with respect to the other of the two electrodes.

[0027] Advantageously, the gap distance of multiple spark gap switches can be effectively adjusted by the same actuation (i.e., action) provided by a pressure-controlled actuator and / or a capacitive actuator. All multiple spark gap switches can be adjusted simultaneously. This not only provides a more reliable design but also results in significantly more precise control over the gap distance. Interlocking adjustment can be performed in different ways.

[0028] The gap distance of multiple (e.g., all) spark gap switches can be adjusted simultaneously by a single action.

[0029] Optionally, the adjusting component includes multiple adjusting subunits, wherein each adjusting subunit is configured to individually adjust the gap distance of one or a group of spark gap switches.

[0030] In some examples, the adjusting member is arranged to move the electrodes of the spark gap switch individually relative to each other. In some examples, each spark gap switch (and / or one or more sets of spark gap switches) may have a dedicated adjusting subunit. Advantageously, the relative difference between the desired / target gap distance of the spark gap switches can be easily controlled.

[0031] Alternatively, the adjusting member is arranged to directly adjust the gap distance by means of a pressure-controlled actuator and / or a capacitive actuator.

[0032] Pressure-controlled / capacitive actuators can be used to directly adjust the gap distance. They offer high actuation force while maintaining a compact design. Therefore, this approach allows for cost-effective designs.

[0033] The direct connection between the pressure-controlled / capacitive actuator and one or more components directly connected to the electrodes, used for adjusting the gap distance, provides a simple design. Such a design can be more reliable and / or require less maintenance.

[0034] Optionally, the adjusting member is arranged to indirectly adjust the gap distance by means of a pressure-controlled actuator and / or a capacitive actuator, wherein the adjusting member includes a mechanical means for converting the displacement of the actuated surface achieved by the pressure-controlled actuator and / or the capacitive actuator into appropriate adjustment of the gap distance.

[0035] The voltage-controlled / capacitive actuator can be configured to indirectly adjust the gap distance. A mechanical device can be configured to provide an indirect connection between the electrodes of the voltage-controlled / capacitive actuator and the spark gap switch of the Marx generator.

[0036] Optionally, the regulating unit includes a bellows with a surface that is resiliently displaced in response to pressure changes in the pressurized gas, wherein the surface is coupled to one of the two electrodes of each spark gap switch, wherein the bellows is sealed, and wherein the pressure-controlled actuator is configured to control the fluid pressure inside the sealed bellows.

[0037] Pressure-controlled actuators can be configured to regulate the pressure inside a sealed bellows. For example, to reduce the clearance distance, the pressure inside the sealed bellows can be increased. This increase in pressure inside the bellows can be caused by fluid flow toward the bellows. The pressure actuator is configured to perform active control by monitoring and controlling the pressure, rather than based on volume.

[0038] The pressure-controlled actuator is configured to provide actuation that results in a change in the clearance distance based on direct / active control of the pressure inside the bellows. In this way, the clearance distance can be precisely adjusted in a robust manner.

[0039] The gas used in the bellows can be, for example, a gas at a pressure that is not very sensitive to temperature changes. If the pressure of the pressurized gas between the electrodes of the spark gap switch decreases (e.g., due to gas loss from leakage), one side of the bellows can expand forward, thereby adjusting and increasing the gap distance between the electrodes of the spark gap switch. If the pressure of the pressurized gas between the electrodes of the spark gap switch increases (e.g., due to temperature increase), one side of the bellows can contract backward, thereby adjusting and decreasing the gap distance between the electrodes of the spark gap switch. This passive adjustment obtained through the bellows can be calibrated so that the distance between the electrodes is adjusted so that the breakdown voltage is maintained within a predetermined range or substantially constant even under conditions of variation related to the pressure of the pressurized gas. The bellows can provide passive compensation. Advantageously, in addition to passive compensation, active control of the output voltage of the Marx generator is achieved using a pressure-controlled actuator. The fluid pressure inside the bellows can be actively controlled using a pressure-controlled actuator, wherein the pressure-controlled actuator is configured to manipulate the fluid pressure within the bellows.

[0040] It should be understood that the bellows can be considered a reversible and expandable body. Various alternative embodiments are envisioned.

[0041] Optionally, the bellows is configured such that compression and expansion of the bellows cause linear movement of a rod connected to the surface of the bellows, and wherein the rod is coupled to a shaft, wherein the adjustment unit is arranged such that movement of the rod causes pivoting movement of the shaft, and wherein one of the two electrodes of each spark gap is connected to the shaft.

[0042] Alternatively, the bellows is a vacuum bellows, which includes a biasing member tensioned between the surface and the wall of the bellows.

[0043] Alternatively, the biasing member is a spring, wherein the biasing force caused by the spring is adjustable.

[0044] Alternatively, the rod is connected to the shaft via a hinge connector, wherein the position of the hinge connector is adjustable.

[0045] Alternatively, the medium used in a capacitive actuator is a substantially incompressible medium. A variety of substantially incompressible media (e.g., liquids) can be used.

[0046] Alternatively, the medium is a hydraulic fluid, such as oil. Capacitive actuators can use a variety of hydraulic fluids.

[0047] Optionally, the regulating unit is configured to adjust the gap distance to obtain the breakdown voltage at a selected potential difference, thereby generating a controlled output voltage.

[0048] Advantageously, in some examples, the output voltage can be set based on the available input power to the Marx generator.

[0049] According to one aspect, the present invention provides a method of operating a Marx generator, wherein the Marx generator includes circuitry comprising at least two capacitors arranged to charge in parallel and discharge in series, wherein during discharge, an output voltage is generated by summing the charging voltages of each of the at least two capacitors, wherein the circuitry includes at least two spark gap switches, wherein each spark gap switch includes two electrodes separated by a gap distance filled with pressurized gas, and wherein each spark gap is configured to allow an electric spark to pass between the electrodes if the potential difference between the electrodes exceeds a breakdown voltage, wherein the method includes: providing an adjustment unit for adjusting the gap distance between the two electrodes of each of the at least two spark gap switches to control the output voltage, wherein the adjustment unit is configured to adjust the gap distance by means of a voltage-controlled actuator and / or a capacitive actuator.

[0050] The output of a Marx generator can be effectively adjusted by using a pressure-controlled actuator and / or a capacitive actuator to adjust the gap distance between the electrodes. The gap distance can be changed in various ways. The relative distance between the electrodes can be adjusted, for example, using linear movement, axial movement, radial movement, or any other type of movement.

[0051] According to one aspect, the present invention provides an electrical pulse drilling system comprising a Marx generator according to the invention, wherein the electrical pulse drilling system includes a controller for operating the Marx generator to output a controlled output voltage.

[0052] In some examples, pneumatic (pressure) lines and / or hydraulic lines may be directed toward the Marx generator to provide pressurized fluid to pressure-controlled actuators and / or to media (e.g., hydraulic oil) to capacitive actuators.

[0053] Optionally, the controlled output voltage is selected based on sensing data obtained by means of a sensing unit, wherein the sensing unit is configured to measure one or more values ​​that indicate or are associated with the characteristics of the surface to be drilled, wherein preferably, the sensing unit is configured at the electric pulse drill bit of the electric pulse drilling system to enable online measurement during drilling.

[0054] In this way, the output of the Marx generator in the electro-pulse drilling system can be dynamically adjusted according to the surface to be drilled (e.g., rock). Advantageously, the efficiency of the drilling operation can be significantly improved. In this way, more cost-effective drilling operations can be performed.

[0055] Optionally, the controlled output voltage is adjusted based on a value indicating the drilling speed achieved by the electrical pulse drilling system.

[0056] The gap distance can be adjusted by the pressure / volume actuator based on the drilling results achieved by the electropulse drilling system. For example, if the drilling speed decreases, the output of the Marx generator can be adjusted to increase the drilling speed again. In some examples, the drilling speed can be maintained within a predetermined range (e.g., substantially constant) in this way.

[0057] Alternatively, the output voltage can be set based on the available input power of the Marx generator.

[0058] According to one aspect, the present invention provides an adjustment unit for use in a Marx generator.

[0059] According to one aspect, the present invention provides an active actuation power stabilizer for a Marx generator.

[0060] According to one aspect, the present invention provides the use of a Marx generator in an electrical pulse drilling system.

[0061] According to one aspect, the present invention provides an apparatus including a Marx generator system according to the present disclosure.

[0062] It should be understood that a Marx generator can be a spark gap switch high voltage generator that includes multiple capacitors arranged to allow parallel charging and series discharging.

[0063] The circuitry of the Marx generator can be configured such that at least two capacitors are charged during charging, and that discharging occurs between at least two spark gap switches, resulting in at least two capacitors being connected in series, such that an output voltage is generated by adding the charging voltages of each of the at least two capacitors. The spark gap switches can be configured to operate in self-breakdown mode.

[0064] It should be understood that any aspects, features, and options described for the Marx generator are equally applicable to the method and the described electropulse drilling system. It will also be clear that any one or more of the foregoing aspects, features, and options can be combined. Attached Figure Description

[0065] The invention will be further illustrated based on exemplary embodiments shown in the accompanying drawings. Exemplary embodiments are given by way of non-limiting description. It should be noted that the drawings are merely illustrative representations of embodiments of the invention given by way of non-limiting example.

[0066] In the attached diagram: Figures 1a and 1b show schematic diagrams of an embodiment of the system; Figure 2 A schematic diagram of an embodiment of the system is shown; Figure 3 A schematic diagram of an embodiment of the system is shown; Figures 4a and 4b show schematic diagrams of an embodiment of the system; Figure 5 A schematic diagram of an embodiment of the system is shown; Figure 6 A schematic diagram of an embodiment of the system is shown; Figures 7a and 7b show schematic diagrams of an embodiment of the system; Figure 8 A schematic diagram of an embodiment of the system is shown; Figure 9 A schematic diagram of an electric pulse drill bit is shown; and Figures 10a and 10b show schematic diagrams of an electric pulse drill bit. Detailed Implementation

[0067] Figures 1a and 1b show schematic diagrams of an embodiment of System 1. System 1 includes a Marx generator 3, which includes circuitry comprising at least two capacitors C arranged to charge in parallel and discharge in series. During discharge, an output voltage is generated by summing the charging voltages of each of the at least two capacitors C. The circuitry also includes at least two spark gap switches 5, each spark gap switch comprising two electrodes 7a, 7b spaced apart by a gap distance G filled with pressurized gas. Each spark gap switch 5 is configured to allow an electric spark to pass between its at least two electrodes 7a, 7b if the potential difference between the two electrodes exceeds a breakdown voltage. The Marx generator includes an adjustment unit 10 configured to adjust the gap distance between the two electrodes of each of the at least two spark gap switches, such as to control the output voltage. The adjustment unit 10 is configured to adjust the gap distance by means of a voltage-controlled actuator and / or a capacitive actuator.

[0068] Figure 1a shows a Marx generator in a charging state, and Figure 1b shows a Marx generator in a discharging state, providing an output pulse. The circuit of the Marx generator includes a series of capacitors C connected in parallel for charging and series for discharging, but other configurations are also possible. When capacitors C are charging, no current flows through resistor R. If the voltage is high enough, a spark can be generated between the electrodes of the spark gap switch, resulting in a series connection of capacitors C in the circuit (see Figure 1b). Current then flows from one capacitor C to the next, and so on, for subsequent stages / branches in the circuit, thereby generating a high-voltage pulse at the output of the Marx generator. The output is located at the end of the circuit. The Marx generator is capable of producing high-voltage sparks and can be used in a wide range of applications (e.g., electrical pulse drilling).

[0069] The distance between the electrodes of a spark gap switch determines the breakdown voltage, which is the voltage required to trigger a spark between the electrodes.

[0070] The adjustment unit 10 can be used to actively adjust the output from the Marx generator. For example, the output can be adjusted / set based on the input power supplied to the Marx generator. Additionally or alternatively, the output can be dynamically adjusted based on sensor data (e.g., for applications involving electrical pulse drilling).

[0071] In some examples, the regulating unit 10 can be used to actively compensate for the effects caused by pressure variations in the pressurized gas. By compensating for the parameters that cause pressure variations in the pressurized gas, a more stable output can be obtained from the Marx generator. The value of the breakdown voltage determines the output voltage / output power of the Marx generator. Advantageously, the breakdown voltage is maintained within a desired predetermined range (e.g., constant) by keeping the pressure of the pressurized gas within a desired predetermined range. In some advantageous examples, this is performed by adjusting the distance between the electrodes that affect the breakdown voltage. This makes it easy and reliable to control the breakdown voltage. Furthermore, such a regulating mechanism can have a relatively simple design, making the Marx generator cheaper and less prone to error.

[0072] To maintain the compactness and stability of the Marx generator, it can have a housing filled with a pressurized gas (such as pressurized nitrogen). However, other dielectric gases, such as air, CO2, rare gases, or gas mixtures, can also be used. By employing higher pressures, a more compact design can be achieved for the Marx generator, as a larger breakdown voltage can be obtained with a smaller size.

[0073] Figure 2 A schematic diagram of a portion of system 1 is shown, which includes a Marx generator 3 with an adjustment unit 10. The adjustment unit 10 includes an adjustment mechanism configured to adjust the gap distance G between the two electrodes 7a, 7b of each of at least two spark gap switches 5. The gap distance G can define a space filled with pressurized gas 13. The adjustment unit 10 includes at least one of a pressure control module or a volume control module, wherein the pressure control module is configured to operate a pressure-controlled actuator to manipulate the fluid actuation pressure to achieve the adjustment of the gap distance, and wherein the volume control module is configured to operate a capacitive actuator to manipulate the actuation volume of the medium to achieve the adjustment of the gap distance. In this example, the adjustment unit 10 includes an adjustment member 15 configured to move one electrode of the two electrodes of at least one spark gap switch relative to the other electrode of the at least one spark gap switch. Advantageously, the adjustment member 15 is moved by means of a pressure-controlled / capacitive actuator 12. The regulating member 15 provides a mechanical connection between the pressure / volume actuator 12 and one of the two electrodes 7b of at least two spark gap switches 5 of the Marx generator. In this example, the Marx generator may include a housing 17, in which an atmosphere of dielectric material is primarily present. Multiple capacitor stages of the Marx generator may be arranged within the housing 17.

[0074] Marx generators can operate more reliably and allow for efficient setting / adjustment of specific power outputs. Furthermore, even at high repetition rates, the durability of Marx generators can be improved because the breakdown voltage can be better actively controlled (e.g., kept constant or within a predetermined range, such as ±40%, ±30%, ±20% of the target value).

[0075] In some examples, the mechanical adjustment of the distance between the electrodes of the spark gap switch can be based on sensor measurement signals. Various types of sensors can be used. For example, indicative or pressure-related sensor signals associated with the pressurized gas can be used to maintain the output of the Marx generator within a desired predetermined range.

[0076] Figure 3 A schematic side view of an embodiment of system 1 is shown, system 1 including a Marx generator 3 having an adjustment unit 10 having an adjustment member adapted to adjust the gap distance G between two electrodes 7a, 7b of each of at least two spark gap switches 5, wherein the adjustment unit 10 is configured to adjust the gap distance by means of a pressure-controlled actuator 12 and / or a capacitive actuator 12. Similar to... Figure 2 In the embodiment shown, the space defined by the gap distance G can be filled with pressurized gas 13.

[0077] The regulating unit 10 includes a pressure-controlled / capacitive actuator 12 configured to manipulate fluid actuation pressure and / or medium actuation volume to perform adjustment / setting of a desired gap distance G to obtain a desired output. In this example, the pressure-controlled / capacitive actuator is configured to move one of the two electrodes of at least one spark gap switch relative to the other electrode of the at least one spark gap switch by means of a rigid rod 16. Various other mechanical transmission elements can be used for this purpose. The regulating member 15 of the regulating unit 10 can provide a direct or indirect mechanical connection between the pressure-controlled / capacitive actuator 12 and one of the two electrodes 7b of at least two spark gap switches 5 of the Marx generator. Figures 4a and 4b show the following perspective views. Figure 3 A schematic diagram of an embodiment of System 1 shown.

[0078] Figure 5 A schematic diagram of an embodiment of a portion of system 1 is shown, which includes an adjustment unit 10 configured to adjust the gap distance by means of a controlled-capacity actuator 12. The controlled-capacity actuator 12 is configured to provide volume control using a hydraulic cylinder. Alternatively or additionally, a controlled-pressure actuator 12 may also be used.

[0079] The adjusting member 15 is arranged such that one of the two electrodes of each spark gap switch moves together relative to the other electrode. Furthermore, in this example, the adjusting member 15 is arranged to indirectly adjust the gap distance by means of a capacitive actuator. A mechanical device is provided for converting the displacement of the actuation surface achieved by the capacitive actuator into a desired adjustment of the gap distance G. In this example, the gap distance G can be considered as the shortest distance between the two electrodes, since the electrodes pivot relative to each other and have convex surfaces. Various other shapes and configurations are conceivable.

[0080] In this example, system 1 is configured such that displacement of the surface of the capacitive actuator causes movement of a rod 27 connected to said surface. Rod 27 is coupled to shaft 29, wherein an adjustment unit is arranged such that movement of rod 27 causes pivoting movement of shaft 29, and wherein one of the two electrodes of each spark gap is connected to shaft 29. Electrodes 7b of the multiple spark gap switches of the Marx generator can move together via the pivoting movement of said shaft 29.

[0081] In this example, the medium used in the capacitive actuator can be (substantially) incompressible. For example, a hydraulic fluid such as oil can be used. Highly precise control over motion, clearance distance G, and thus the output of the Marx generator, can be achieved in a robust, cost-effective, and accurate manner.

[0082] A controlled-capacitance actuator is configured to provide actuation that results in a change in the gap distance based on direct / active control of the medium volume. For example, a controlled-capacitance actuator may include a piston for achieving volumetric displacement of the medium, through which the gap distance can be controlled.

[0083] Figure 6 A schematic diagram of a portion of system 1 is shown. The regulating member 15 includes an regulating element 21 arranged to move one electrode 7b of each spark gap switch 5 relative to the other electrode 7a. The regulating member 15 includes a bellows 23 with a surface 25 that is elastically responsive to pressure changes in the pressurized gas 13, wherein the surface is coupled to one of the two electrodes 7b of each spark gap switch 5.

[0084] The bellows 23 can be configured such that compression and expansion of the bellows 23 cause a linear movement M of the rod 27 connected to the surface 25 of the bellows 23. The rod 27 can be coupled to a pivotally arranged shaft 21. The adjustment mechanism 11 can be arranged such that movement of the rod 27 causes pivoting movement of the shaft 21, indicated in the figure by rotation R. One of the two electrodes 7b of each spark gap 5 is connected to the shaft 21, thus enabling efficient and reliable adjustment of the gap distance. In this way, articulation for adjusting the gap distance G based on pressure changes of the pressurized gas 13 can be readily obtained.

[0085] In this example, rod 27 is connected to pivotally arranged shaft 21 via hinge connector 29. Hinge connector 29 is configured such that the position of the connection point is adjustable.

[0086] In this example, the bellows 23 is filled with pressurized fluid. Furthermore, the bellows 23 includes a biasing member 29 (e.g., an internal compression spring) tensioned between the surface and wall of the bellows 23. Different types of biasing members can be used. Different fluid pressures can be used in the chamber / housing 31 of the bellows 23. The bellows has another surface 33 at its other end, which is fixed, for example, mounted on a wall or surface 35. The biasing member can have an adjustable biasing force, for example, by using one or more other biasing members to induce a reaction force.

[0087] Such embodiments of the present disclosure allow for the simultaneous adjustment of the gap distances of all spark gap switches at the same time, without requiring dedicated gaps for each individual spark gap switch. This results in a more reliable arrangement. Furthermore, the design of the adjustment unit 10 can be significantly simplified. For example, multiple spark gap switches may not all have the same initial / reference gap distance, such as the minimum distance between electrodes (e.g., set using a setting plate between them). For example, for multiple spark gap switches, the initial / reference gap distance can be in the range of 1 to 1.5 mm. For example, the first spark gap switch in the first stage can have an initial gap distance of 1.2 mm, the second spark gap switch in the second stage can have an initial gap distance of 1.1 mm, the third spark gap switch in the third stage can have an initial gap distance of 1.4 mm, and so on. The relative initial gap distances can be maintained by jointly changing and adjusting the gap distances of multiple spark gap switches, for example, by causing a pivoting motion of the shaft of the pivoting arrangement. The standard distance between the electrodes of each spark gap switch can remain the same; however, the change in gap distance can be the same for each of the multiple spark gap switches.

[0088] Furthermore, if the gap distance of the spark gap switch changes under the influence of vibration, this can also have the effect of altering the breakdown voltage and thus the output power of the Marx generator. Advantageously, this mechanical arrangement for adjusting the gap distance is less sensitive to vibration. In this way, a reliable power stabilizer can be obtained, which can effectively ensure that the preset power is maintained during the use of the Marx generator (e.g., throughout the drilling process for electrical pulse drilling).

[0089] The adjustment unit 10 is configured to adjust the gap distance by means of a pressure-controlled actuator and / or a capacitive actuator. A fluid line can be provided to the housing of the Marx generator for the pressure-controlled / capacitive actuator 12. Advantageously, the gap distance can be adjusted pneumatically (see gas) or hydraulically (see liquid medium) using the pressure-controlled / capacitive actuator 12.

[0090] In this example, the bellows includes a (hermetically sealed) housing / container, allowing the fluid pressure inside the bellows to be regulated using a pressure actuator. This enables a reliable and robust control arrangement.

[0091] The degree to which the distance between the electrodes changes according to the pressure variation of the pressurized gas can be adjusted by changing the pressure inside the bellows. By actively changing the pressure inside the bellows, desired overcompensation can be achieved. Consequently, the pressure variation inside the bellows also causes a power variation. Therefore, advantageously, the bellows can be used as an output power regulator. Additionally or alternatively, a mechanical arrangement configured to convert stroke displacement into a change in gap distance can also be tuned to adjust the degree of change in the distance between the electrodes.

[0092] Figures 7a and 7b show schematic diagrams of a portion of system 1. Figure 6 The examples show different states of the regulating device. Figure 7a shows the first state, in which the gap distance between the first electrode 7a and the second electrode 7b of the spark gap switch is minimal. Figure 7b shows the second state, in which the movable surface 25 of the bellows 23 has been displaced by means of the pressure-controlled / capacitive actuator 12. As a result, a linear stroke displacement S of the rod 27 is achieved, which causes a pivoting movement of the shaft 21, thereby increasing the gap distance G.

[0093] One of the two electrodes of each spark gap switch can be mounted on a pivotally arranged shaft 29 (e.g., a cylindrical shaft). The electrode on the pivotally arranged shaft 29 can have a spherical head. Pivoting movement of the pivotally arranged shaft can cause a change in the distance between the two electrodes of the spark gap switch.

[0094] If the pressure of the pressurized gas increases, the moving surface 25 of the bellows 23 is pulled back, and the pivoting shaft rotates counterclockwise. The electrodes arranged on the pivoting shaft are positioned closer to the other electrodes arranged on the spark gap switches. As a result, the distance between the electrodes of the spark gap switches decreases in a predictable manner (see calibration), resulting in a shorter path for the spark to travel between at least two electrodes. Advantageously, a reliable and accurate passive mechanical adjustment mechanism can be obtained, which is less prone to error. For example, in some applications, electronic components may fail or extensive shielding may be required due to harsh electromagnetic interference (EMI) environments. Furthermore, the adjustment unit 10 of system 1 is configured to actively adjust the gap distance by means of a pressure-controlled actuator that changes the fluid pressure inside the bellows. Therefore, the fluid pressure in the bellows is adjustable to actively control the output power of the high-voltage generator. For example, a pressure line can be connected to the bellows, through which the pressure inside the bellows can be varied over time. For example, the pressure inside the bellows can be increased, decreased, or maintained to adjust / set the distance between the electrodes of a spark gap switch, which in turn affects the output power of the voltage generator. For instance, when a high-voltage generator is used for electrical pulse drilling, some surfaces (e.g., specific rocks) may require different output powers to perform efficient and / or effective drilling. Additionally or alternatively, the drilling speed can also be controlled in this way without the need for an electric actuator at the electrical pulse drill bit. Controlling the pressure inside the bellows to adjust the output power of the high-voltage generator (see Marx generator) provides pneumatic control, which is beneficial in a variety of applications. Due to the relatively harsh conditions at the drill bit (see EMI, vibration, high temperature, etc.), for example, during electrical pulse drilling, electronic equipment may require excessive shielding or may be more prone to error. For example, by changing the gas pressure (e.g., vacuum pressure) in the bellows, the distance between the electrodes can be precisely changed, and the output power can be effectively varied as needed.

[0095] Figure 8 A schematic diagram of a portion of system 1 is shown in perspective. Adjustment component 15 is used to collectively adjust the distance between the electrodes of the plurality of spark gap switches 5. Rotation of shaft 21 causes a linked relative displacement of the electrodes 7a, 7b of the plurality of spark gap switches 5.

[0096] The distance between electrodes 7a, 7b of each spark gap switch 5 in a multi-stage Marx generator can be adjusted together using a single action. Each stage has a spark gap switch, which may require a specific initial distance. One of the two electrodes of the multiple spark gap switches in the multi-stage can be mounted on a pivotally arranged shaft. In this way, the distance between the electrodes of each of the multiple spark gap switches can be adjusted jointly, while ensuring the initial distance between the electrodes of each of the multiple spark gap switches. The initial distance can be, for example, the result of calibration. In other words, the electrode distances of the multiple spark gap switches can be adjusted by a single movement. This provides a highly reliable adjustment mechanism to compensate for the effects caused by pressure changes in the pressurized gas.

[0097] Advantageously, adjustable spark gap switches can provide increased reliability, repeatability, and lifespan. The time required between maintenance cycles can be increased, resulting in a more cost-effective design.

[0098] Alternatively, a vacuum bellows can be used for passive compensation. Therefore, advantageously, the operation of the bellows no longer depends on changes in the ambient temperature, which would cause pressure changes in the gas inside the bellows. However, alternatively, the output of the Marx generator can be actively controlled by adjusting the (vacuum) pressure inside the bellows. Advantageously, the pressure regulation inside the bellows can be achieved using a pressure-controlled actuator.

[0099] For different gases, the breakdown voltage as a function of the pressurized gas pressure can be given in a diagram of Pashin's law. At a constant temperature in a uniform field, the spark potential of a gas depends only on the product of the gas pressure and the electrode spacing. In other words, the spark potential is a function of the product of pressure and distance, and depends neither solely on pressure nor solely on distance, i.e., V0 S =f(pd). This V S -pd curves can be provided for different gases. Different dielectric gases can be used in the Marx generator.

[0100] The curve has a left branch and a right branch. The right branch is essentially linear and allows for precise control, such as maintaining the breakdown voltage substantially constant or within a predetermined range (e.g., ±10% of the initial value), even under varying parameters that might affect the fluid pressure between the electrodes of the spark gap switch. Using such a linear component in control is advantageous. It can be seen that for lower pressures, the curve is relatively steep, making it very sensitive to changes and resulting in more difficult or even unreliable control in those ranges. In this graph, for example, for nitrogen at a pressure of 12 bar, the breakdown voltage is approximately 17 kV / mm.

[0101] If the pressure of the pressurized gas increases, the breakdown voltage increases. This can be actively compensated for by the regulating unit 10 using a pressure-controlled / capacitive actuator to reduce the distance between the electrodes of the spark gap switch.

[0102] It should be understood that, in some examples, in contrast to joint adjustment, the adjustment member may have multiple adjustment sub-units, each of which is configured to individually adjust the gap distance of one or a group of spark gap switches.

[0103] Figure 9 A schematic diagram of an embodiment of an electrical pulse drilling system 51 is shown. The drilling system 51 includes a controller 60 configured to operate the electrical pulse drilling system. The system 51 includes a drill bit 53 having an end 55, wherein at least two electrodes 57 are arranged at the end 55 of the drill bit 53. The system 51 also includes an actuation system 59 configured to move the drill bit to the vicinity of a surface 61 to be broken. The system 51 also includes a high-voltage generator configured to apply a voltage between the electrodes 57, thereby causing one or more discharges between the electrodes 57, said one or more discharges resulting in one or more electric arcs 63 for breaking the surface 61. The high-voltage generator is a Marx generator.

[0104] In the example shown, drill bit 53 is positioned within borehole 52. In some cases, the generated voltage (not shown in the figure) is separate from drill bit 53. However, it is also conceivable that the voltage generator is attached to or integrated into the drill bit of the drilling system 51. In some examples, drill bit 53 and voltage generator form an integral unit directly connected to each other. In some examples, drill bit 53 and voltage generator are separate and can be remotely positioned relative to each other, for example, by wiring. In some examples, drill bit 53 and voltage generator are separate to allow movement relative to each other. Many types of arrangements are possible.

[0105] It should be understood that the front end of drill bit 53 is not necessarily a plane containing the electrode 57 extending therefrom. The front end may only include protruding electrodes (e.g., a rod with electrode ends). Sufficient spacing may be provided between the protruding electrodes 57 to allow debris to be discharged by flushing.

[0106] Electrical pulse drilling equipment with a Marx high-voltage generator may require the components of the Marx generator to be housed within a closed housing filled with a gas at a preset pressure (e.g., dry nitrogen at a pressure). The preset pressure can be chosen high enough to keep the housing size finite. The pressure of the pressurized gas within the housing determines the breakdown voltage (kV / cm), and thus also the distance between the various components. Higher pressurized gas pressure results in a higher breakdown voltage for the spark gap switch. Additionally, the spark gap switch can be arranged within the same housing where the pressurized gas is dominant. Advantageously, an adjustment unit 10 is provided for adjusting the output of the Marx generator by changing the electrode gap distance within the Marx generator, wherein the adjustment unit is configured to adjust the gap distance by means of a pressure-controlled actuator and / or a capacitive actuator. In some advantageous examples, the gap distance is adjusted to achieve breakdown at a certain breakdown voltage (see triggering the spark gap switch). The spark gap switch can also be mounted in a separate housing (e.g., one or more tubes) with separate pressurized gases (e.g., all at the same or different pressures).

[0107] The Marx generator can be integrated into the body of the electric pulse drill bit or constructed externally. In both cases, the active adjustment unit according to this disclosure can be arranged within the Marx generator.

[0108] The breakdown voltage of the spark gap switch can be determined by the gas pressure, and therefore the available power output of the Marx generator at the EMP drill bit also depends on this. Furthermore, the pressure of the pressurized gas also depends on its temperature. The temperature of the pressurized gas in the EMP drill bit can change significantly during (deep) EMP drilling operations (e.g., due to geothermal activity), which can significantly alter the breakdown voltage and thus the output power. The regulating unit according to this disclosure can actively compensate for this and prevent such changes in breakdown voltage and output power. Furthermore, passive regulation obtained by the compensation unit can be provided, which, for example, compensates for the gap distance based on pressure changes, temperature changes, etc. In this way, the output can be passively maintained within a predetermined range (e.g., substantially constant) by the compensation unit. However, if desired, the regulating unit allows the output voltage to be actively set / regulated using a pressure-controlled / capacitive actuator. In some examples, the regulating unit can also be configured to actively compensate for the output of the Marx generator and maintain the Marx generator's output within the predetermined desired range.

[0109] The regulating unit 10 according to this disclosure can provide effective and reliable output control of the Marx generator. Pressure changes in the pressurized gas at the electrodes of the spark gap switch in the Marx generator housing can be captured and actively compensated for. For this purpose, one or more sensors can be used, which can capture indicators of the pressurized gas pressure. In some examples, a pressure-controlled / capacitive actuator is used to adjust the gap distance between the electrode pairs of the spark gap switch based on the said pressure changes. For example, pressure changes may be caused by gas loss from the Marx generator over time (e.g., leakage, poor packaging, etc.); temperature changes in the gas within the Marx generator due to environmental conditions; and / or any other reason.

[0110] In some examples, the regulating unit includes a bellows according to this disclosure. In some examples, the bellows is a bellows with a gas chamber. Optionally, the gas chamber is in fluid communication with an external unit via a fluid line. For example, the line may be connected to a pump for controlling the fluid pressure inside the bellows (see pressure-controlled actuator). One side of the bellows may be fixedly mounted to the structure. The other side may be allowed to move. A compression spring may be installed in the chamber of the bellows. The biasing force of the compression spring may be adjusted to a reference gas pressure in the Max generator. The expansion or compression of the compression spring may be adjusted such that linear movement of the other side is obtained when the pressure varies within a predetermined pressure range.

[0111] By using a vacuum in the bellows (see Significant under Pressure), bellows tuning and setting become easier and largely independent of ambient temperature. Therefore, a more predictable and reliable regulation mechanism can be obtained in this way. Active control of the gap distance can be achieved using a pressure-controlled actuator. Compression or expansion of the bellows can be transmitted substantially linearly to an eccentric rotating shaft via a rod. One electrode of a spark gap switch can be mounted on this rotating shaft. This shaft increases or decreases the opening of the spark gap switch (see Gap Distance Between Its Electrodes) based on the gas pressure of the pressurized gas surrounding the spark gap switch. Multiple spark gap switches can be regulated collectively by arranging one electrode of each switch on this rotating shaft. Rotation of the shaft causes synchronized movement of one electrode of each of the multiple spark gap switches. Advantageously, passive compensation can be achieved in such an example. Active control (active regulation / compensation) can be achieved using a pressure-controlled actuator that can, for example, change the fluid pressure inside the bellows by means of an external conduit or fluid communication.

[0112] Figures 10a and 10b show schematic diagrams of an embodiment of drill bit 53. In Figure 10a, the Marx generator system 1 is integrated within drill bit 53. In Figure 10b, the Marx generator system 1 is spaced apart from drill bit 53. In this example, the distance between voltage generator 1 and drill bit 53 can be adjustable, for example, the distance can be increased when drill bit 53 is further lowered in the borehole during the electro-pulse drilling process. Voltage generator 1 and drill bit 53 can be connected via connecting member 80.

[0113] For example, the pressure of the pressurized gas can increase due to geothermal energy at certain depths. Temperature may also change due to the operation of the electric pulse drill bit. For example, internal heating can also affect the temperature of the pressurized gas. The increased pressure caused by the increased temperature will lead to an increase in breakdown voltage. Without the regulating unit according to this disclosure, the electric pulse drill bit will stop working at some point. Therefore, by employing the method and system according to this disclosure, electric pulse drill bits with Marx generators can be used at greater depths, thereby actively counteracting, but not limited to, the adverse effects of geothermal heating using a regulating unit configured to adjust the gap distance by means of a pressure-controlled actuator and / or a capacitive actuator.

[0114] A more compact design can be achieved by using higher pressures on the pressurized gas. This allows for, for example, smaller electric pulse drill bits. However, higher pressures may make the device more sensitive to effects such as temperature variations and gas leaks. A variety of gases can be used in the Marx generator. The gas can be a dielectric gas. For example, the gas can be dry nitrogen (see Highly Electrically Insulating Gases). However, other gases (such as rare gases) can also be used. In some examples, a gas with a breakdown voltage greater than 1000 Volt / mm at 1 atm is desired. Various dielectric gases can be used. Examples of other gases that can be used are argon, helium, sodium, sulfur hexafluoride, air, CO2, etc.

[0115] In some examples, the fluid line is connected to the electric pulse drill bit where the Marx generator is located. However, it is also conceivable that the pressure-controlled / pressure-controlled actuator is configured to operate without a fluid line.

[0116] It should be understood that various pressures (e.g., vacuum pressure) can be used inside the bellows. Optionally, the vacuum pressure is less than 0.1 bar. In some examples, the vacuum pressure is less than 0.01 bar. In some examples, the effect of temperature is further reduced by using a vacuum pressure of 0.001 bar or even lower. The choice of vacuum pressure can be highly dependent on the application using the Marx generator. For example, the temperature of the pressurized gas can rise to higher temperatures due to geothermal heat during electrical pulse drilling. The vacuum pressure can be selected to reduce the effect of the increased temperature on the stroke displacement, thus providing more robust and accurate control. The vacuum pressure can be selected such that temperature variations cause deviations that fall within the resolution of the control unit.

[0117] In some examples, the pressure inside the bellows is related to the pressure of the pressurized gas. Optionally, the pressure inside the bellows is at least 10 times lower than the pressure of the pressurized gas, more preferably at least 20 times lower, and even more preferably at least 30 times lower.

[0118] It should be understood that a spark gap switch can be understood as a spark switch or a spark electrode switch.

[0119] It should be understood that electrical pulse drilling can also be understood as electrical pulse drilling, electric arc drilling, electric breaking drilling, pulsed arc plasma drilling, pulsed arc drilling, plasma arc drilling, plasma pulse drilling, plasma pulse geological drilling, etc. The term "drilling" and its derivatives can be replaced with "well drilling," and vice versa. The term can be interpreted as the act of creating holes, cutting, or creating indentations in some surface or material. The term drilling or burring can also mean breaking up and removing fragments of the surface or material from the drilled area during the drilling process.

[0120] It should be understood that gap distance can be considered as the gap, spacing, clearance, crack, interval, or void between the electrodes of a spark gap switch.

[0121] In the following description and claims, the term “link” and its derivatives may be used. “Link” is used to indicate that two or more elements cooperate or interact with each other, but they may or may not have an intermediate physical or electrical component between them.

[0122] As used in the claims, unless otherwise stated, ordinal adjectives such as "first," "second," "third," etc., are used to describe common elements. This merely indicates different examples of similar elements and is not intended to imply that the elements so described must be in a given sequence in time, space, order, or any other way. The accompanying drawings and the foregoing description provide examples of embodiments. Those skilled in the art will understand that one or more of the described elements can be well combined into a single functional element. Alternatively, certain elements may be divided into multiple functional elements.

[0123] When referring to measurable values ​​such as parameters, quantities, durations, etc., the terms “about” or “approximately” as used herein are intended to cover variations of + / -10% or less, preferably + / -5% or less, more preferably + / -1% or less, provided that such variations are suitable for implementation in the disclosed invention. It should be understood that the values ​​referred to by the modifiers “about” or “approximately” are themselves specifically and preferably disclosed.

[0124] It should be understood that the method may include computer-implemented steps. All of the above steps can be computer-implemented. Embodiments may include a computer device in which the process is performed. The invention also extends to computer programs suitable for practicing the invention, particularly computer programs on or in a carrier. The program may be in the form of source code or object code, or any other form suitable for implementing the process according to the invention. The carrier may be any entity or device capable of carrying the program. For example, the carrier may include a storage medium such as a ROM, such as a semiconductor ROM or a hard disk. Furthermore, the carrier may be a transmissible carrier, such as electrical or optical signals, which can be transmitted via cable or optical fiber or by radio or other means (e.g., via the Internet or the cloud).

[0125] Some embodiments may be implemented, for example, using a machine or a tangible computer-readable medium or article of writing that may store instructions or a set of instructions, which, when executed by a machine, may cause the machine to perform the methods and / or operations according to the embodiments.

[0126] Various embodiments can be implemented using hardware components, software components, or a combination of both. Examples of hardware components may include processors, microprocessors, circuits, application-specific integrated circuits (ASICs), programmable logic devices (PLDs), digital signal processors (DSPs), field-programmable gate arrays (FPGAs), logic gates, registers, semiconductor devices, chipsets, etc. Examples of software may include software components, programs, applications, computer programs, application programs, system programs, machine programs, operating system software, mobile applications, middleware, firmware, software modules, routines, subroutines, functions, computer-implemented methods, processes, software interfaces, application programming interfaces (APIs), methods, instruction sets, computational code, computer code, etc.

[0127] In this document, the invention is described with reference to specific examples of embodiments thereof. However, it will be apparent that various modifications, variations, substitutions, and alterations may be made therein without departing from the spirit of the invention. For the purpose of clarity and concise description, features are described herein as part of the same or separate embodiments; however, alternative embodiments having combinations of all or some of the features described in these separate embodiments are also contemplated and are to be understood as falling within the framework of the invention as outlined in the claims. Therefore, the specification, drawings, and examples are to be considered illustrative rather than restrictive. The invention is intended to include all substitutions, modifications, and variations falling within the scope of the appended claims. Furthermore, many of the elements described are functional entities that can be implemented as discrete or distributed components or combined with other components in any suitable combination and location.

[0128] In the claims, any reference numerals placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of other features or steps besides those listed in the claims. Furthermore, the words "a" and "an" should not be construed as limited to "only one," but are used to mean "at least one," and do not exclude multiples. The fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used advantageously.

Claims

1. A Marx generator comprising a circuit, the circuit comprising at least two capacitors arranged to be charged in parallel and discharged in series, wherein, During discharge, an output voltage is generated by adding the charging voltages of each of the at least two capacitors, wherein the circuit comprises at least two spark gap switches, wherein each spark gap switch comprises two electrodes separated by a gap distance filled with a pressurized gas, and wherein each spark gap switch is configured to allow an electrical spark to pass between the two electrodes of the spark gap switch if a potential difference between the two electrodes exceeds a breakdown voltage, and wherein the Marx generator comprises an adjustment unit configured to adjust the gap distance between the two electrodes of each of the at least two spark gap switches in order to control the output voltage, wherein the adjustment unit is configured to adjust the gap distance by means of a pressure-controlled actuator and / or a volume-controlled actuator.

2. The Marx generator of claim 1, wherein, The adjustment unit comprises at least one of a pressure control module or a volume control module, wherein the pressure control module is configured to operate the pressure-controlled actuator to manipulate a fluid actuation pressure in order to effect the adjustment of the gap distance, wherein the volume control module is configured to operate the volume-controlled actuator in order to manipulate an actuation volume of a medium to effect the adjustment of the gap distance.

3. The Marx generator of claim 1 or 2, wherein, The adjustment unit comprises an adjustment member configured to move one of the two electrodes of at least one spark gap switch relative to the other of the two electrodes of the at least one spark gap switch.

4. The Marx generator of claim 1, 2 or 3, wherein, The adjustment member is arranged to move the other of the two electrodes of each spark gap switch collectively relative to one of the two electrodes of each spark gap switch.

5. The Marx generator of any of the preceding claims, wherein, The adjustment member is arranged to adjust the gap distance directly by means of the pressure-controlled actuator and / or the volume-controlled actuator.

6. The Marx generator of any of the preceding claims, wherein, The adjustment member is arranged to adjust the gap distance indirectly by means of the pressure-controlled actuator and / or the volume-controlled actuator, wherein the adjustment member comprises a mechanical device for converting an actuation surface displacement effected by the pressure-controlled actuator and / or volume-controlled actuator into a sufficient adjustment of the gap distance.

7. The Marx generator of any of the preceding claims, wherein, The adjustment unit comprises a bellows comprising a surface that is elastically responsively displaceable under the influence of a pressure change of the pressurized gas, wherein the surface is coupled to one of the two electrodes of each spark gap switch, wherein the bellows is sealed, and wherein the pressure-controlled actuator is configured to control a fluid pressure inside the sealed bellows.

8. The Marx generator of claim 7, wherein, The bellows is configured such that a compression and expansion of the bellows results in a linear movement of a rod connected to the surface of the bellows, and wherein the rod is coupled to a shaft, wherein the adjustment unit is arranged such that a movement of the rod results in a pivotal movement of the shaft, and wherein one of the two electrodes of each spark gap is connected to the shaft.

9. The Marx generator of any of the preceding claims 2 to 8, wherein, The medium used in the volume-controlled actuator is a substantially incompressible medium.

10. The Marx generator of claim 9, wherein, The medium is a hydraulic liquid, such as oil.

11. The Marx generator of any of the preceding claims, wherein, The adjustment unit is configured to adjust the gap distance to obtain a breakdown voltage at a selected potential difference, thereby generating a controlled output voltage.

12. A method of operating a Marx generator, wherein, The Marx generator comprises a circuit comprising at least two capacitors arranged for charging in parallel and discharging in series, wherein during discharging an output voltage is generated by adding the charging voltage of each of the at least two capacitors, wherein the circuit comprises at least two spark gap switches, wherein each spark gap switch comprises two electrodes separated by a gap distance filled with pressurized gas, and wherein each spark gap is configured to allow an electrical spark to pass between the electrodes in case the potential difference between the electrodes exceeds a breakdown voltage, the potential difference between the electrodes exceeds a breakdown voltage, wherein the method comprises providing an adjustment unit for adjusting the gap distance between the two electrodes of each of the at least two spark gap switches to control the output voltage, wherein the adjustment unit is configured to adjust the gap distance by means of a pressure-controlled actuator and / or a volume-controlled actuator.

13. An electric pulse drilling system comprising the Marx generator according to claims 1 to 11, wherein, The electrical pulse drilling system comprises a controller for operating the Marx generator to output a controlled output voltage.

14. The electrical pulse drilling system of claim 13, wherein, The controlled output voltage is selected based on sensing data obtained by means of a sensing unit, wherein the sensing unit is configured to measure one or more values indicative of or associated with a characteristic of the surface to be drilled, wherein preferably the sensing unit is configured at the electrical pulse drill head of the electrical pulse drilling system such that online measurements can be made during drilling.

15. The electrical pulse drilling system of claim 13 or 14, wherein, The controlled output voltage is adjusted based on a value indicative of a drilling speed achieved by the electrical pulse drilling system. The controlled output voltage is adjusted based on a value indicative of a drilling speed achieved by the electrical pulse drilling system.

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