Apparatus and method for generating a plasma in an aqueous environment

An apparatus for supplying a medical instrument for the treatment of biological tissue due to the action of a plasma, the apparatus comprising:

• a generator to output a high-frequency ac voltage to an outlet configured to be connected to the instrument,
• a power supply that is connected to the generator to supply said power supply with an operating voltage,
• a control device configured to control one or both of the generator and the power supply, with a measuring device configured to determine the electrical resistance of the instrument connected to the outlet,
• wherein the control device is configured to specify, at least for a time period, at least one of the operating voltage, the power to be output to the instrument, and the maximum current deliverable to the instrument consistent with the determined electrical resistance, and to control one or both of the power supply and the generator accordingly,
• wherein the control device is configured, after a failed ignition test, to maintain a specified pause interval during a wait phase and to then start another ignition test,
• wherein the control device is configured to detect an electrical work supplied to the instrument,
• wherein the control device is configured to detect an approach of the instrument placed in a lumen toward the biological tissue and to interrupt the wait phase and start another ignition test, provided the control device is in the wait phase.

An apparatus for supplying a medical instrument for the treatment of biological tissue due to the action of a plasma, the apparatus comprising:

• a generator to output a high-frequency ac voltage to an outlet configured to be connected to the instrument,
• a power supply that is connected to the generator to supply said power supply with an operating voltage,
• a control device configured to control one or both of the generator and the power supply, with a measuring device configured to determine the electrical resistance of the instrument connected to the outlet,
• wherein the instrument comprises an electrode and the electrical resistance of the instrument comprises a characteristic resistance, wherein the control device is configured to detect the type of instrument or a shape of the electrode by determining the characteristic resistance of the instrument,
• wherein the control device is configured to specify, at least for a time period, at least one of the operating voltage, the power to be output to the instrument, and the maximum current deliverable to the instrument consistent with the determined characteristic resistance of the instrument, and to control one or both of the power supply and the generator accordingly.