Plasma generation system

Abstract

The power supply circuit is used for generating cold plasma; plasma may be selected for therapeutic use. The generation of cold plasma occurs at the distal end of a catheter-like device that is flexible, narrow (e.g., less than 5 millimeters in diameter) and extends longitudinally into a plurality of body cavities, e.g., 50 to 100 centimeters. The cable for power transfer is part of a power generation circuit whose intrinsic impedance is the primary influence and limitation of the time constant of a synchronous RC circuit whose resonant frequency synchronizes the power generation frequency. In some embodiments, an induction transformer coupling to the synchronization / transmission line circuit is used to generate a voltage gain. In some embodiments, the transformer coupling is divided into multiple stages. This may actually achieve a high transmission frequency with a higher gain, a reduced sensitivity to changes in the distal portion of the synchronous RC circuit, and / or a longer transmission line compared to a single-stage transformer configuration.

Description

[0001] Related Applications

[0002] This application is a continuation of U.S. patent application No. 18 / 130,163 filed on April 3, 2023, which is a continuation-in-part (CIP) of U.S. patent application No. 17 / 866,700 filed on July 18, 2022 (now U.S. Patent No. 11,627,652 issued on April 11, 2023).

[0003] This application is also a continuation-in-part (CIP) of U.S. patent application No. 18 / 129,116 filed on March 31, 2023, which is a continuation-in-part (CIP) of U.S. patent application No. 17 / 971,737 filed on October 24, 2022 (now U.S. Patent No. 11,621,587 issued on April 4, 2023), which is a continuation-in-part (CIP) of U.S. patent application No. 17 / 866,700 filed on July 18, 2022 (now U.S. Patent No. 11,627,652 issued on April 11, 2023).

[0004] This application is also related to commonly filed International Patent Application entitled "Configurable Plasma Generation System" (Attorney Docket No. 95982).

[0005] The contents of each of the above applications are incorporated herein by reference as if fully set forth herein in their entirety.

[0006] FIELD AND BACKGROUND OF THE INVENTION

[0007] The present invention, in some embodiments thereof, relates to the field of plasma generation, and more particularly, but not exclusively, to the generation and therapeutic delivery of cold plasma.

[0008] Non-thermal atmospheric plasma (NTAP), also known as cold atmospheric plasma (CAP), is an ionized gas near room temperature consisting of various neutral and charged species. It is used in a wide variety of applications and industries, including medicine where its beneficial properties are well established. The application of NTAP on tissues exerts complex and unique effects at both the cellular / tissue level and the systemic level.

[0009] NTAP can be generated by dielectric barrier discharge (DBD), in which a flowing gas (usually an inert gas such as helium or argon) is ionized by passing through electrodes to which a high voltage is periodically applied. The electrodes are covered by a dielectric barrier so that no direct ohmic path is created between the driving source and the target tissue to which it is applied. Summary of the invention

[0010] According to one aspect of some embodiments of the present disclosure, a power supply circuit for a non-thermal plasma generator is provided, the circuit comprising: a gain transformer comprising a primary coil and a secondary coil; a drive circuit electrically connected to drive current through the primary coil; a load circuit having a distal end and a proximal end, the distal end comprising a plasma generation site, the proximal end coupled to the secondary coil of the gain transformer; wherein the load circuit comprises at least one decoupling transformer, the at least one decoupling transformer inductively connecting the plasma generation site and the secondary coil.

[0011] According to some embodiments of the present disclosure, the load circuit has an impedance that determines a frequency at which the load circuit oscillates in response to the current generated in the secondary coil.

[0012] According to some embodiments of the present disclosure, the load circuit synchronizes the oscillation of the drive circuit.

[0013] According to some embodiments of the present disclosure, the oscillation of the load circuit is synchronized by feedback from the gain transformer.

[0014] According to some embodiments of the present disclosure, the frequency of the oscillation of the load circuit is high enough so that the plasma generation at the plasma generation site is not extinguished within at least one complete oscillation cycle.

[0015] According to some embodiments of the present disclosure, the gain provided by the gain transformer is at least 20.

[0016] According to some embodiments of the present disclosure, the at least one decoupling transformer provides a gain that is not greater than 1 overall.

[0017] According to some embodiments of the present disclosure, the at least one decoupling transformer overall provides a gain that is at least 2 times smaller than a gain provided by the gain transformer.

[0018] According to some embodiments of the present disclosure, the gain transformer and at least one coupling transformer include air or ferrite cores.

[0019] According to some embodiments of the present disclosure, the at least one decoupling transformer includes a plurality of decoupling transformers.

[0020] According to some embodiments of the present disclosure, the gain transformer and at least one coupling transformer isolate the plasma generation site from ground.

[0021] According to some embodiments of the present disclosure, the load circuit includes: a transmission line, and a remote transformer among the at least one decoupling transformer, including a secondary coil of the remote transformer, the secondary coil being inductively connected to a primary coil of the remote transformer and connected to a proximal side of the transmission line; the drive circuit: being electrically connected to the proximal side of the transmission line through the primary coil and the secondary coil of the remote transformer, and providing an electrical signal with an operating frequency between 1 and 10 MHz to the transmission line, the electrical signal being transmitted to a remote end of the transmission line with an operating amplitude of at least 0.5 kV RMS; and wherein the impedance of the secondary coil of the remote transformer combined with the capacitance of the transmission line is small enough so that a circuit portion including the transmission line and the secondary coil operates in a resonant manner when receiving the electrical signal.

[0022] According to some embodiments of the present disclosure, when the transmission line is disconnected, the driving circuit stops generating the electrical signal, but when multiple values ​​of the capacitance of the transmission line vary within a range with a difference of at least 10% between its minimum value and its maximum value, the driving circuit maintains generating the electrical signal.

[0023] According to some embodiments of the present disclosure, the operating amplitude is at least 1 kV RMS.

[0024] According to some embodiments of the present disclosure, the transmission line is at least 50 centimeters long and is flexible.

[0025] According to some embodiments of the present disclosure, the load circuit provides a feedback signal to the driving circuit via a feedback network.

[0026] According to some embodiments of the present disclosure, the oscillation of the load circuit synchronizes the drive circuit through the feedback network to generate the electrical signal at the operating frequency.

[0027] According to some embodiments of the present disclosure, the power circuit is provided together with a gas supply chamber leading to the plasma generation site along the transmission line, and the gas supply chamber and the transmission line together become multiple elements of a flexible probe with a total diameter of less than 10 mm.

[0028] According to some embodiments of the present disclosure, the plasma generation site generates non-thermal plasma when powered by the electrical signal.

[0029] According to some embodiments of the present disclosure, the at least one decoupling transformer together with the gain transformer constitutes a plurality of transformers, and the plurality of transformers connect the proximal end of the transmission line to a low voltage signal oscillating at the operating frequency, wherein a voltage amplitude of the low voltage signal is at least 20 times smaller than the operating amplitude.

[0030] According to some embodiments of the present disclosure, the primary coil of the gain transformer has an inductance in the range of about 1 to 5 μH, and the secondary winding of the gain transformer has an inductance in the range of about 1000 to 5000 μH.

[0031] According to some embodiments of the present disclosure, the gain transformer includes a feedback winding, which provides a feedback signal to the driving circuit through a feedback network, and wherein the feedback winding has an inductance in the range of about 1 to 10 μH.

[0032] According to some embodiments of the present disclosure, the feedback signal synchronizes the oscillation of the drive circuit to the operating frequency, and is received at the feedback winding through the load circuit at the electrical oscillation frequency of the transmission line.

[0033] According to some embodiments of the present disclosure, the secondary winding of the remote transformer has an inductance in the range of about 20 to 80 μH, and the primary winding of the remote transformer has an inductance in the range of about 5 to 20 μH.

[0034] According to some embodiments of the present disclosure, the secondary winding of the remote transformer is connected to a plurality of conductors of the transmission line through a plurality of electrical contacts.

[0035] According to some embodiments of the present disclosure, the power supply circuit includes: a pulse modulation circuit, which is operable to modulate the operating frequency to a lower frequency, wherein the lower frequency includes a frequency in the range of 0.1 to 1 KHz.

[0036] According to an aspect of some embodiments of the present disclosure, there is provided a method of decoupling gain and multiple frequency limits of non-thermal plasma generation, comprising: providing an output electrical signal to a plasma generation site, the output electrical signal having an operating frequency and a voltage amplitude sufficient to generate plasma; wherein the plasma generation site is electrically connected to an input electrical signal oscillating at the operating frequency through at least two transformer stages, and the voltage of the input electrical signal is at least 20 times lower than the voltage of the output electrical signal.

[0037] According to some embodiments of the present disclosure, the voltage amplitude is at least 1 kV.

[0038] According to some embodiments of the present disclosure, the operating frequency is between 1 and 10 MHz.

[0039] According to some embodiments of the present disclosure, the plasma generating site is connected to the input electrical signal via a transmission line, and the oscillation of the circuit including the transmission line synchronizes the oscillation of the input electrical signal.

[0040] According to an aspect of some embodiments of the present invention, there is provided a non-thermal plasma generator, comprising: a gain transformer comprising a primary coil and a secondary coil; a drive circuit electrically connected to drive a current through the primary coil; a load circuit having a distal end and a proximal end, the distal end comprising a plasma generation site for generating non-thermal plasma, the proximal end coupled to the secondary coil of the gain transformer; wherein the load circuit comprises at least one decoupling inductor, the inductance provided comprising an inductance connected in parallel with the secondary coil, and an inductance connected in parallel with the plasma generation site.

[0041] According to some embodiments of the invention, the load circuit has an impedance that determines a frequency at which the load circuit oscillates in response to the current generated in the secondary coil.

[0042] According to some embodiments of the invention, the load circuit synchronizes an oscillation of the drive circuit.

[0043] According to some embodiments of the invention, the oscillation of the drive circuit is synchronized by feedback from the gain transformer.

[0044] According to some embodiments of the present invention, the frequency of the oscillation of the load circuit is high enough so that the plasma generation at the plasma generation site is not extinguished within at least one complete oscillation cycle.

[0045] According to some embodiments of the present invention, the non-thermal plasma generator comprises: a pulse modulation circuit operable to modulate the frequency of the oscillation at a lower frequency in the range of 0.1 to 1 KHz.

[0046] According to some embodiments of the present invention, the gain transformer provides a gain of at least 20.

[0047] According to some embodiments of the present invention, the at least one decoupling inductor comprises at least one decoupling transformer, and the at least one decoupling transformer provides a gain that is not greater than 1 as a whole.

[0048] According to some embodiments of the present invention, the at least one decoupling inductor comprises a plurality of decoupling transformers, wherein a gain provided by the plurality of decoupling transformers in total is at least 2 times smaller than a gain provided by the gain transformer.

[0049] According to some embodiments of the present invention, the gain transformer comprises an air or ferrite core.

[0050] According to some embodiments of the invention, the at least one decoupling inductor comprises a plurality of decoupling transformers.

[0051] According to some embodiments of the present invention, the at least one decoupling inductor comprises an inductor coil connected in parallel to the secondary coil and to the plasma generation site.

[0052] According to some embodiments of the present invention, the drive circuit stops oscillating when the plasma generation site is disconnected from the load circuit, but keeps oscillating when multiple values ​​of the frequency of oscillation of the load circuit vary within a range having a difference of at least 10% between a minimum value and a maximum value of the range.

[0053] According to some embodiments of the present invention, when current is driven through the primary coil of the gain transformer, an operating voltage amplitude of at least 1 kV RMS is generated at the plasma generation site.

[0054] According to some embodiments of the invention, the transmission line is at least 50 centimeters long and is flexible.

[0055] According to some embodiments of the present invention, the power circuit is provided together with a gas supply chamber leading to the plasma generation site along the transmission line, and the gas supply chamber and transmission line together form multiple components of a flexible probe with a total diameter of less than 10 mm.

[0056] According to some embodiments of the present invention, the at least one decoupling inductor together with the gain transformer constitutes one or more transformers, and the one or more transformers transmit the operating voltage to the plasma generation region, and the plasma generation region has an amplitude that is at least 20 times greater than the voltage amplitude in the primary coil of the gain transformer.

[0057] According to some embodiments of the present invention, the primary coil of the gain transformer has an inductance in the range of about 1 to 5 μH, and the secondary coil of the gain transformer has an inductance in the range of about 1000 to 5000 μH.

[0058] According to some embodiments of the present invention, feedback from the gain transformer is provided by a feedback winding of the gain transformer, and wherein the feedback winding has an inductance in the range of approximately 1 to 10 μH.

[0059] According to some embodiments of the present invention, the at least one decoupling inductor includes at least one decoupling transformer, and a remote side coil of the at least one decoupling transformer has an inductance in the range of approximately 20 to 80 μH, and the remote side coil is a coil of a remote decoupling transformer of the at least one decoupling transformer having a primary coil, and the primary coil has an inductance in the range of approximately 5 to 20 μH.

[0060] According to some embodiments of the present invention, at least one decoupling inductor is connected to the plasma generation site via a plurality of releasable electrical contacts.

[0061] Unless otherwise defined, all technical and / or scientific terms used herein have the same meanings as those generally understood by those of ordinary skill in the art to which the present disclosure belongs. Although methods and materials similar or equivalent to the methods and materials described herein can be used in the practice or testing of the embodiments of the present disclosure, exemplary methods and / or materials are described below. If there is a conflict, the patent specification (including definitions) shall prevail. In addition, materials, methods and embodiments are for illustrative purposes only and are not necessarily restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Some embodiments of the present invention are described herein by way of example only and with reference to the accompanying drawings. With specific reference now to the drawings, it should be emphasized that the details shown are only examples and are used for illustrative discussion of the embodiments of the present disclosure. In this regard, the description in conjunction with the drawings will enable those skilled in the art to clearly understand how to practice the embodiments of the present disclosure.

[0063] In the attached picture:

[0064] Figure 1A Schematically illustrates a plasma generating device according to some embodiments of the present invention;

[0065] Figure 1B is a waveform diagram of typical current and voltage of low frequency (<100 KHz) atmospheric pressure plasma according to some embodiments of the present invention;

[0066] Figure 1C Plot typical high frequency (e.g. >1 MHz) current and voltage waveforms for atmospheric pressure plasma according to some embodiments of the present invention;

[0067] FIG. 2A to FIG. 2B An in vivo plasma application system is schematically represented to illustrate potential problems in the design of a plasma generation system that are addressed in some embodiments of the present invention;

[0068] Figure 3A A block diagram schematically illustrates a resonant high voltage plasma generating system according to some embodiments of the present invention;

[0069] Figure 3B A flow chart schematically illustrating an operating method of a resonant high voltage plasma generating system according to some embodiments of the present invention;

[0070] Figure 3CA circuit diagram schematically illustrating a resonant high voltage plasma generating system according to some embodiments of the present invention;

[0071] Figure 3D Schematically showing C at gain levels M=1 and M=2 according to some embodiments of the present invention equiv C coax The reduction of theoretical dependence;

[0072] FIG. 4A to FIG. 4B schematically illustrates a resonant high voltage plasma generating system according to some embodiments of the present invention; and

[0073] FIG. 5A to FIG. 5B A variation of a resonant high voltage plasma generating system using a decoupling coil according to some embodiments of the present invention is schematically illustrated. DETAILED DESCRIPTION

[0074] The present invention, in some embodiments thereof, relates to the field of plasma generation, and more particularly, but not exclusively, to the generation and therapeutic delivery of cold plasma.

[0075] Overview:

[0076] An aspect of some embodiments of the invention relates to the design of circuits operable at high frequency power generation for plasma generation. In some embodiments of the invention, an alternating electric field is used to generate non-thermal atmospheric plasma (NTAP) via dielectric barrier discharge (DBD).

[0077] Alternation helps overcome the alternating "screening" effect caused by charge migration. During the positive cycle of voltage (anode electrode), high-mobility electrons generated in the plasma are attracted to the electrode barrier. This generates an electric screening effect, causing the plasma to be quickly extinguished. In the opposite cycle, when the electrode acts as a cathode, these electrons become the ionization source to reignite the plasma until the attraction of positive ions to the cathode screens them again. In order to achieve continuous plasma generation, the electric field (proportional to the voltage applied to the electrode) continuously alternates between the polarities of these two cycles. Although on a fine time scale, the plasma is emitted in the form of discrete plasma pellets, the frequency of the alternation is high enough that the plasma output appears to be continuous.

[0078] However, this has a potential impact on efficiency, since the extinguished plasma must be reignited in each half cycle. During each cycle, the energy required to maintain the ignited plasma is significantly lower than the energy required to reignite the plasma. One way to mitigate this is to reduce the time period during which the mobile ions / electrodes are moving to enhance the shielding effect, which can in principle be achieved by increasing the cycle frequency. The frequency above which transient shielding effects no longer cause intermittent extinguishing of plasma generation is referred to herein as the "transition frequency".

[0079] The frequency of the transition from pellet plasma to continuous plasma depends on the physical configuration of the system (e.g., electrode size, gas chamber size, and / or electrode configuration), as well as gas composition and environmental effects, such as pressure and temperature. For typical DBD plasma jet applications, the transition frequency is typically around 1 megahertz (MHz). Even at this frequency, subthreshold shielding effects of plasma extinction can still interfere with ionization efficiency. Therefore, with other parameters being equal, the power output of the generated plasma may continue to increase at higher frequencies.

[0080] Thus, the plasma power can be controlled by adjusting the plasma generation frequency. For example, the plasma generation frequency can be controlled within a range from somewhere close to the device transition frequency to about ten times higher than the frequency. For example, the frequency can be varied within a range from about 1 MHz up to about 10 MHz, or within some portion of this range.

[0081] Frequency tuning in actual circuits is subject to various constraints that are determined or influenced by the remaining conditions of plasma generation and performance. In some embodiments of the present invention, a plasma generator is operated at an AC (e.g., sinusoidal) voltage with a root mean square (RMS) value of about 0.5 to 2 kilovolts (kV) (e.g., 1 kV RMS).

[0082] "Continuous plasma" as used herein refers to the continuity of a single high frequency signal cycle of 100 kHz or higher. Optionally, the term refers to a sequence of multiple such cycles. However, such a sequence of cycles may be interrupted; for example, pulse width modulation (PWM) is performed at a frequency in the range of about 0.1 to 1 kHz (e.g., 600 Hz). The duty cycle can be adjusted to any suitable percentage up to 100% (e.g., 66%). In some embodiments, a plasma generation system may include a PWM circuit, for example, a PWM circuit that can operate within at least such a range.

[0083] In addition to the specific characteristics of plasma generation, the performance and efficiency of a generator generally depends largely on the load characteristics and the required bandwidth. Specifically, a generator may be most efficient at a certain operating frequency of the circuit. For a plasma generator, the operating frequency may be in the range of, for example, 1 MHz to 10 MHz; but the efficiency of other frequencies in the range may be much lower. The operating frequency may be equal to or close to the natural resonant frequency of the circuit. Additionally or alternatively, the design of a generator may sacrifice efficiency and performance (e.g., frequency stability, distortion, and / or power loss) in order to support a wider range of resistive and capacitive loads.

[0084] In some embodiments of the present invention, a plasma generator is configured for use in a variety of therapeutic field applications. The configuration particularly includes a spatial separation of a plasma generating unit from a power generating unit that drives it. The power generating unit may be too bulky to be placed near the organ and / or patient being treated. In intra-body plasma applications, a plasma delivery probe is pushed and / or passed through a variety of confined spaces, and the electrical drive circuit of the probe is too large to fit in the probe itself.

[0085] The effectiveness of plasma generated outside the body (relatively close to the driving circuit) and delivered into the body may be reduced due to the short half-lives of many plasma products. The electrical characteristics of the plasma may prevent it from being transported more than a few centimeters into the body.

[0086] Alternatively, a high voltage signal is transmitted to a probe distal end where plasma is generated and then applied to the target tissue. Signal transmission can be performed via a coaxial cable, thereby allowing electrical signals to be safely transmitted over relatively long distances (e.g., one meter or longer, e.g., at least 1, 2, 3, 4, or 5 meters) while maintaining power and signal integrity. Coaxial cable structures have potential advantages in miniaturization and flexibility when used for in vivo applications, for example, in many catheter-type devices, which can be advanced to a distance of several centimeters (e.g., 10, 50, 100 centimeters or more) beyond an opening in the body such as a natural orifice and / or a keyhole incision.

[0087] As further described below, while the use of a coaxial transmission line is a practical solution for transmitting power to a relatively distant plasma generation site, it becomes part of an interlocking system of parameters that, in some embodiments of the invention, are considered to limit the transmission frequency to around a certain resonant frequency of the transmission line (and the RC network of which it is a part) for optimal efficiency.

[0088] If the transmission line is part of an RC network whose resonant frequency is far from the power transfer frequency, the transmission line itself may have excessive losses (e.g., causing heating, which may reach a point where operation is limited, such as reducing duty cycle), and / or the power is transferred inefficiently into the line, which may increase the size, cost and / or robustness requirements of the power supply. At resonance, the inductance and capacitance can cancel each other and reduce the resistive power losses.

[0089] When transmitting through a small diameter transmission line, the effect of electrical losses generating heat may be more significant, for example due to the corresponding reduction in its thermal mass. In some embodiments of the present invention, the diameter of the transmission line (e.g., less than 5 mm, 3 mm, less than 2 mm, or less than 1.5 mm) is a limit on the minimum diameter of the body cavity that can be accessed, as long as the transmission line is used as part of a probe advanced through the body cavity to a plasma delivery target.

[0090] Problems also arise due to the high slew rates required to provide a high voltage signal (e.g., 0.5 kV RMS or more) at a high frequency (e.g., 1 MHz or more). If resonant drive is not used, it may be difficult to make the transmission load follow such a slew rate. In some embodiments, the resonant drive also provides a built-in power shut-down function in the event that the transmission line is accidentally disconnected or severely damaged, because this will interrupt the generation of the feedback signal and thus affect the power generation frequency.

[0091] The considerations just described lead to a system of interrelated engineering constraints. The following is a simple example of how the constraints interlock, which will be explained in more detail below. (1) To achieve a plasma discharge, the voltage requirement of the plasma generator may be 1 kV RMS. (2) To achieve 1 kV RMS from a reasonable input side voltage of 20 to 33 V, the transformer gain of the generator should be in the range of about 30 to 50 (optionally greater than 20, greater than 25, or greater than 30). (3) The ratio is also proportional to the ratio of the square roots of the two inductors (primary and secondary) used in the transformer that can generate the gain. (4) However, the output side inductance (secondary inductance) is limited to a lower level by the same efficiency constraint (5), which drives the selection of a high resonant frequency to deliver power to the plasma generation probe; for example, a frequency of about 2 MHz. If the inductance is too high, the frequency requirement cannot be met without significantly reducing the capacitance, but (6) in some embodiments, this is mainly provided by the inherent capacitance of the coaxial cable required to transmit the power. Finally, (7) the input side inductance (primary inductance) is constrained to be even lower than the secondary inductance. But this may be an unrealistically low value. This may manifest itself in design pressures to forgo one or more requirements such as low input voltage, high operating frequency, or long transmission lines.

[0092] In some embodiments of the present disclosure, the design pressure is alleviated by another solution: using a dual transformer configuration, which includes a gain transformer and a decoupling transformer (which itself can be divided into one or more stages). The gain transformer is free to use practical reasonable inductance values, creating voltage gain by inserting the decoupling transformer. In fact, isolation ultimately allows the output side of the gain transformer to have low capacitance. Then, since no gain is required on the isolation transformer (or only a relatively low gain is required), the primary inductance of the isolation transformer can be equal to the secondary inductance, rather than being forced to an unrealistically small value due to the requirement to generate voltage gain. In some embodiments, the decoupling effect is generated using the same inductor coil in parallel with the plasma load (the far end) and another inductor coil (the near end, for example, a secondary coil of the gain transformer). This can simulate the effect of inserting a unity gain transformer while avoiding the losses caused by non-ideal inductive coupling.

[0093] As a potential practical consequence, introducing an isolation stage may provide potential benefits in one or more of the following areas:

[0094] Decouples constraints on voltage gain and operating frequency.

[0095] Allows for increased coaxial cable length without sacrificing the ability to match other design constraints.

[0096] Reduce frequency variations due to changes in load impedance.

[0097] Details of these potential advantages are described further below.

[0098] Notably, in some embodiments, electrical isolation from ground is provided by coupling the plasma generation site (receiving a high voltage) to its power source through one or more ground isolation transformers.

[0099] Before explaining at least one embodiment of the present disclosure in detail, it should be understood that the present disclosure is not necessarily limited in its application to the construction details and the arrangement and / or method of components set forth in the following description and / or shown in the accompanying drawings. The features described in the present disclosure, including the features of the present invention, can be implemented in other embodiments or practiced or performed in various ways.

[0100] Plasma therapy device:

[0101] Reference now Figure 1A , which schematically shows a plasma generating device 100 according to some embodiments of the present invention.

[0102] In some embodiments, the plasma generation device 100 includes a high voltage power generator 201 and an ionized gas supply source 61, which is connected to a plasma probe assembly 62. The high voltage power generator 201 provides an ionization voltage to the plasma probe assembly 62 through a cable 203 (for example, a coaxial cable or other electrical conduit with controlled impedance). The ionized gas supply source 61 supplies ionized gas to the plasma probe assembly 62 through a pipe 72. The supplied gas may include, for example, one or more inert gases, such as neon, argon, or helium; and / or other gases suitable for ionization into a plasma plume 90. Optionally, the cable 203 and the pipe 72 are integrated into a single cable unit, which is connected to the plasma probe assembly 62. Optionally, the high voltage power generator 201 and the ionized gas supply source 61 are housed integrally.

[0103] The plasma probe assembly 62 optionally includes a handle 80. The handle 80 is optionally provided with a plurality of controllers 81, 82 for controlling the activation of the probe conduit 73 and / or the plasma delivery end 66, for controlling the functions of the power generator 201, and / or for controlling the delivery of ionized gas from the gas supply 61. Optionally, the plasma probe assembly 62 physically integrates the power supply function and the gas delivery function into the probe conduit without the need for a dedicated handle. In some embodiments, the probe conduit 73 includes a lumen for delivering ionized gas and a high voltage transmission line (e.g., a continuation of the cable 203 and the pipe 72). In some embodiments, the probe conduit includes multiple lumens, for example, a lumen for delivering ionized gas attached to the gas supply 61, and a lumen for optionally cleaning (removing) ionized gas under suction. In some embodiments, any one or more lumens of the probe conduit 73 are optionally used as a working channel by inserting a tool. In some embodiments, the handle 80 includes one or more ports 83 for guiding these tools into a lumen of the probe conduit 73.

[0104] In some embodiments of the present invention, the probe catheter 73 and plasma delivery tip 66 are sized and configured (e.g., safety configuration) for delivering non-thermal plasma to a location within the body. The location within the body can be remote relative to an insertion point, for example, 25 centimeters (cm) or more from an insertion point into the body; for example, 80 cm, 100 cm, or 120 cm. As long as the plasma tip 60 includes a site for plasma generation (as in some embodiments), the device must provide an ionization level voltage (e.g., 1 kilovolt (kV) or more) to the tip 60. This length may place a limit on the minimum capacitance of the cable 203.

[0105] In some embodiments, the probe catheter 73 (including the lumen for delivering the ionized gas and the high voltage transmission line) has an overall diameter of less than 12 millimeters (mm), less than 10 mm, less than 8 mm, or less than 5 mm. The narrower the overall diameter, the narrower the smallest body cavity that the probe catheter can pass through as a catheter; for example, a ureter, blood vessel, or other subcutaneous passage to a target treatment site.

[0106] Reference now Figure 1B , which is a typical current and voltage waveform of low frequency (<100KHz) atmospheric pressure plasma. Figure 1C , which illustrates typical high frequency (e.g., >1 megahertz (MHz)) current and voltage waveforms for atmospheric pressure plasma.

[0107] Although the excitation voltages 103 and 101 are both sinusoidal in both cases, Figure 1BIt can be seen from FIG. 1 that in each half cycle, when the plasma pellet is ignited, the current 104 has a peak value. Figure 1C In the higher frequency example of , the current waveform 102 more closely tracks the input voltage (with a phase shift) because the continuous plasma generation maintains a uniform resistance in the plasma plume.

[0108] Plasma high voltage generator:

[0109] Reference now FIG. 2A to FIG. 2B , which schematically illustrates an in vivo plasma application system 200, illustrates potential problems in the design of a plasma generation system that are addressed in some embodiments of the present invention. Figure 2A is a schematic block diagram of system 200, and Figure 2B express Figure 2A A component level implementation scheme of the schematic block diagram.

[0110] In the example shown, the generator 201 and the coaxial cable 203 operate together to generate a high voltage drive signal for the plasma gun. The generator 201 includes a primary coil drive circuit 204, which includes an amplifier 208, is activated by the input voltage 202, and drives the primary coil of the transformer 205. In some embodiments, the coaxial cable 203 includes a flexible electrical transmission line, which is connected to the secondary coil of the transformer 205, thereby conducting the high voltage to a plasma generation site near its terminal, where the plasma generated constitutes a plasma load 206.

[0111] To generate the plasma, the ionized gas is also conducted to the plasma generation site, optionally through a conduit extending along the coaxial cable 203 to reach the plasma generation site. In some embodiments, the coaxial cable 203 is inserted into a body to be treated (e.g., inserted along the lumen of a body cavity), and a high voltage is delivered simultaneously with the ionized gas to generate the plasma. The voltage is alternating at a high frequency; for example, the frequency is several thousand hertz, such as 100 kilohertz (kHz) or higher. It is worth noting that dosimetry of the generated plasma is optionally achieved by one or more arrangements and / or methods. For example, the signal used to generate the plasma (e.g., its power, frequency and / or waveform) can be monitored by a dosimetry circuit (e.g., a circuit in communication with an optional dosimeter 505), which is arranged to measure the signal before it enters the coaxial cable 203 and / or at another location in the circuit of the overall system. Optionally, the plasma itself can be monitored by a sensor (e.g., optical or electrical) near the plasma generation site (plasma load 206) and in communication with the dosimeter 505.

[0112] Figure 2B The implementation scheme shows that the capacitance C of the coaxial cable 203 coax In some embodiments, the capacitance is a capacitance that adds significant capacitance to the total load driven by the generator 201 through the primary coil drive circuit 204. This capacitance is a general characteristic of any type of transmission line.

[0113] As the target operating frequency increases, the added capacitance eventually becomes limiting the bandwidth that generator 201 can achieve at a given voltage amplitude. At relatively low frequencies of a few kHz, for a practical cable length of 2 to 3 meters (m), the added capacitance C coax is insignificant.

[0114] However, to increase the frequency into the megahertz (MHz) range, there are potential advantages to using a resonant generator configuration, such as Figure 2B As shown. The resonant generator relies on the cable capacitance (together with the transformer 205) to form an "LC" type resonant circuit that can be adjusted to a specific resonant frequency. The generated frequency is fed directly to the plasma generation part together with the high voltage provided from the high side of the transformer (the secondary winding of the transformer).

[0115] It should be noted that this method of power signal generation is qualitatively different from methods of generating a power signal at a frequency that is simply selected to match the time constant of the load. In this case, matching is required to effectively transmit the generated signal. Integrating the load and its electrical characteristics into the generator circuit itself has a potentially adverse effect on the flexibility of the power generator. For example, the frequency selection adjustment in a standard power supply should match the load impedance to achieve efficient transmission into the load, but the frequency of the power supply signal itself can be relatively freely selected without hindering its generation. When the load becomes part of the signal generating circuit, adjusting the frequency outside a limited range means adjusting the electrical characteristics of the load and the driving circuit in tandem. If the adjustments are not coordinated, the signal generating circuit may stop generating a signal at all.

[0116] In some embodiments of the invention, matching plays a role beyond enabling efficient transmission of the power signal; it also affects the generation of the power signal itself. The frequency of the power signal is generated essentially (i.e., as a matter of proximate cause, not just a matter of predetermined selection) according to the load characteristics. Change the load and the frequency will also change. This is not to say that the power supply will be included in the C coax The power signal generation itself is impaired by changing the load characteristics too much. In the absence of load-side resonance at all, the power signal generation ceases due to the extreme mismatch of the network.

[0117] In fact, the transmission line capacitance is a key component of the timing signal providing portion of the power signal generator, so that the transmission line itself can accept the frequency of the power signal being generated (and can also accept the frequency after generating the frequency), otherwise, there would be no valid power signal to accept. In fact, the load side of the circuit synchronizes the oscillation of the driving circuit, which is different from being selected to match its oscillation frequency.

[0118] In short, the capacitor C coax Together with the secondary coil inductance L3, they serve as the main parameters determining not only them but also the time constant of the oscillation of the drive circuit 204 on the primary side of the coil 205. However, at sufficiently high frequencies, this theoretical circuit becomes difficult to implement in practice; for example, because voltage gain requirements force the selection of impractically low inductances on the primary coil of the transformer 205 (including the inductors L1, L2).

[0119] exist Figure 2B In the simplified electrical schematic of FIG. 2 , the primary coil driving circuit 204 is powered by an input voltage source 202, for example, a DC voltage stepped up to 100 V. A transformer unit 205 is connected between the driving circuit 204 and the transmission line (coaxial cable 203). It consists of three coupled inductors: primary coil L1, feedback coil L2 and secondary coil L3.

[0120] The output 206 of the amplifier 208 is connected to the primary coil L1 through the decoupling capacitor C4, and the feedback of the amplifier 208 is connected to the input 207 through the compensation network C_FB and L_FB in the opposite polarity. The feedback network including L3 and C_FB is matched by the feedback network including L2, L_FB and C_FB. coax The time constant of the LC network generates a sinusoidal resonance with the following frequency:

[0121]

[0122] Considering a typical use case, for example, there may be a target resonance of 2 megahertz (MHz). The typical capacitance of a 2 meter (m) coaxial cable may be, for example, about 200 picofarads (pF). In view of this, the inductance of the secondary coil may be selected to be 31 microhenries (μH).

[0123] In some embodiments, the capacitance of the transmission line (the transmission line includes, for example, a coaxial cable, a twisted pair cable, or other conductor configuration) is at least 50 pF, 100 pF, 150 pF, or 200 pF. In some embodiments, the length of the transmission line is at least 50 centimeters (cm), 100 cm, 150 cm, or 200 cm. The inductance of the secondary coil is selected in a corresponding proportion.

[0124] As a further design parameter, a modest operating high voltage of 1 kV RMS may be specified at the plasma load 206, but higher operating voltages may be required, such as at least 1.5 kV RMS or at least 2 kV RMS.

[0125] For reasonable input voltages, the gain ratio of the transformer 205 will be in the range of about 30 to 50. Since the gain ratio is proportional to the square root of the inductance ratio, the primary coil inductance is limited to the range of about 0.01 to 0.03 μH:

[0126]

[0127] It is impractical to use such low primary-side inductance in transformer design to withstand such high voltages. Physical limitations usually result in a single-winding inductor of a few nanohertz (nH) having a maximum size of only a few millimeters (e.g., 4 mm or less). The corresponding transformer, even if constructed in a certain way, must be at many target voltages to handle huge current loads (0.01 μH is approximately equivalent to 0.1 Ω at 2 MHz), resulting in transformer saturation, as well as other parasitic effects such as skin effect. There are also concerns about heating and electrical isolation. Increasing the input voltage (allowing the gain to be reduced while maintaining the target output voltage) significantly reduces the generator efficiency (also causing heating) and becomes impractical beyond a certain point.

[0128] At more modest frequencies, the restrictions are relaxed enough that transformer 205 can be of practical use. For example, for a plasma generator unit driven by 1 kV RMS at 1 MHz into a 100 pF cable, the following drive circuit can be used: secondary side inductance of 100 μH, primary side inductance of 1 μH (resulting in a gain of about 10), and input voltage of 90 V. The transformer's feedback coil inductance is usually less important, but is usually about the same as the inductance of the primary side coil.

[0129] In the above example, if the capacitance of the coaxial cable 203 is modified so that C coax If the capacitance is 100pF (other components remaining constant), further reductions in capacitance are expected to result in a sharp increase in frequency, reduced efficiency, and possibly even a complete loss of resonance. Similarly, increasing the cable capacitance (e.g., by increasing its length) will result in a decrease in frequency and loss of efficiency. In either case, the loss in efficiency is due to the difference between the feedback (C_FB, L_FB, and L2) LC network and the main (L3 and C coax ) is caused by mismatch between LC networks.

[0130] High voltage generator with dual transformer stage:

[0131] Reference now Figure 3A and Figure 3C , which schematically illustrates a resonant high voltage plasma generation system 300 according to some embodiments of the present invention. Figure 5A and Figure 5B , which schematically illustrates a variation of a resonant high voltage plasma generating system 300 using a decoupling coil 501 according to some embodiments of the present invention. Figure 2A Compared with the block diagram, Figure 3A and Figure 5A The generator 301 divides the transformer 205 into two transformer stages: a gain transformer 305A, and a decoupling transformer 305B or a decoupling coil 501. Figure 3A and Figure 3C Many of the descriptions also apply to Figure 5A and Figure 5B The present invention is a plurality of embodiments of the present invention, and is appropriately changed to adapt to the replacement of the decoupling transformer 305B with the decoupling coil 501. This replacement is related to the further content below.

[0132] In some embodiments, this allows relatively high capacitance loads to be driven while retaining the potential advantages of a resonant architecture to achieve high frequency and potentially true sinusoidal output while generating plasma.

[0133] Considering the combination of the drive circuit 204 (including the amplifier 308, the output 306 and the feedback input 307) and the gain transformer 305A, the basic resonance is achieved by matching the time constant of the LC network of L3 and C5 to the feedback LC network including (C_FB, L_FB and L2). C5 can be selected to be a small value (for example, in the range of ten times 1 to 5pF). This allows the corresponding secondary coil inductance L3 to be significantly higher. This also allows the primary coil inductance and / or the feedback coil inductance (for example, L1 and / or L2) to be significantly higher, possibly into a practical range, thereby allowing gains that are not available at frequencies of, for example, 1 to 2MHz. In some embodiments, the inductance range of the primary coil L1 is about 1 to 5μH, the inductance range of the secondary coil L3 is about 1000 to 5000μH, and the inductance range of the feedback coil L2 is about 0.1 to 10μH.

[0134] The rest of the circuit delivers a high frequency, high voltage signal to the load. Capacitor C6 decouples the generated signal. For example, it can measure from a few tenths of a nanofarad (nF) to a few hundred nanofarads (e.g., in a range of 0.1 to 900 nF; for example, 0.5 to 2 nF, 2 to 10 nF, 0.1 to 10 nF, 5 to 20 nF, 20 to 100 nF, 50 to 500 nF, or another capacitance range). Relatively low capacitance has the potential advantage of increasing the speed of system response, such as in terms of oscillation frequency and voltage regulation rate (meaning that the voltage reaches its driven value faster because there is less capacitance to charge). Relatively high capacitance has the potential advantage of reducing general unstable characteristics, such as a tendency to exceed the expected voltage and may not always reach the same voltage (e.g., cycle instability, and / or unstable operating mode).

[0135] In addition, an additional decoupling transformer 305B is used, which has a primary-side inductor L4 and a secondary-side inductor L5. Optionally, the transformer is configured for unity gain (L4=L5, optionally selected to be within ten times of about 100μH, for example, a value in the range of 20 to 200μH). Alternatively, the transformer can be used as a second-stage gain. For example, by setting L4 to a value in the range of about 5 to 20μH and setting L5 to a value in the range of about 20 to 80μH; this can effectively achieve a second-stage gain of 1 to 4 (for example, 2). Finally, by L5 and C coax The resulting LC network is designed to match the resonant frequency set by the drive circuit 204 and the gain transformer.

[0136] Dose determination is optionally performed using a dosimeter 505; for example, using Figure 2A One or more implementations described.

[0137] In some embodiments, the decoupling transformer 305B ( Figure 3A and Figure 3C ) is provided by a single decoupling coil 501 ( Figure 5A and Figure 5B ) is performed. It will be appreciated that in an embodiment where a decoupling transformer 305B provides unity gain, ideal performance may be lost due to the non-ideal coupling between the primary side and the secondary side. This may include efficiency losses. However, in some embodiments, the decoupling coil 501 is used as an alternative equivalent to the unity gain decoupling transformer 305B; that is, it is equivalent in terms of providing the function of an inductor that affects the resonant frequency of the circuit. This substitution provides the potential advantage of avoiding transformer losses while maintaining certain potential advantages described in the following discussion (i.e., the advantage of not relying on gains other than one).

[0138] Two pairs of drawings of embodiments ( Figure 3A and Figure 3C As a pair, Figure 5A and Figure 5B As another pair) have in common a feature of separating the impedance of the plasma probe from the impedance characteristics of the gain transformer. More specifically, they separate the limitations of the probe lead capacitance (coaxial cable capacitance) from the limitations of the gain transformer design that affect characteristics such as system operating voltage, carrier frequency and / or efficiency. They may have the common feature that each includes an inductor connected between multiple conductors of the coaxial cable 203 and / or in parallel with the plasma load 206; and includes an inductor connected in parallel with a secondary coil of the transformer 305A (having secondary coil inductance L3) and / or in parallel with the capacitor C5. In FIG. 5A to FIG. 5B In the case of the embodiment of the present invention, each of the "inductances connected in parallel" defined in this way is embodied as the same inductance provided by the same inductor element (e.g., an inductor coil), and Figure 3A and Figure 3C In the case of the embodiment of the present invention, there are two separately provided inductive elements (e.g., two inductive coils of a transformer). Therefore, in either case, at least one decoupling inductor is provided, the inductance provided by the decoupling inductor includes an inductance connected in parallel with the secondary coil and an inductance connected in parallel with the plasma generation site.

[0139] Although it may be convenient to provide each inductive element as a single inductive coil, there is no inherent obstacle to providing the inductive element as a plurality of inductive sub-elements arranged in electrical series and / or electrical parallel in other configurations, as these configurations may be suitable for providing a target effective inductance that affects the rest of the circuit. There is also no particular obstacle to partial sharing and partial separation of separately defined inductors, which is optional in some embodiments of the invention. In some embodiments, some non-shared portions of the differently defined inductors may optionally be provided in the form of a transformer having a non-unity gain.

[0140] There are some electrical differences due to the substitutions; however, these can be reasonably understood not to impair or distort the basic function of the circuit. For example, it can be noted that Figure 3C In the embodiment, each coil providing inductance L4, L1 is only conductively connected on one side, whereas the embodiment using decoupling coil 501 is actually conductively connected on both sides. However, the use of unity gain means that (again, ideally) there is no potential difference in voltage across the coils in any case, so the conductive connection does not affect their behavior. The differences in voltage and / or phase that may occur in the non-ideal case of an embodiment using a decoupling transformer 305B are not particularly dependent or essential to the function of the device.

[0141] There may also be differences in the current carried by the individual coils. Optionally, the decoupling coil 501 is designed (eg, with a heavier conductor) to carry a higher current (eg, more than 2x) than the individual coils of the decoupling transformer 305B alone can carry.

[0142] One or more of these configurations can achieve at least three significant potential advantages over conventional resonant transformer configurations.

[0143] First, the coupling between frequency and gain is relaxed by adding additional design degrees of freedom. FIG. 2A to FIG. 2B In the design:

[0144]

[0145] The capacitor C coax is ultimately absorbed into the design requirement fixed constant because it is limited to a relatively large value. This yields the inverse relationship already described between frequency and inductance L1 and design gain. Increasing the frequency requires reducing L1 and / or gain to levels that may produce unrealistic consequences for the construction and / or operation of the device.

[0146] Using a second transformer stage introduces the option of using C5 as a compensation capacitor (an additional design freedom):

[0147]

[0148] Second, it is to relax the restrictions on the length of coaxial cables. As mentioned earlier, C coax It may be thought that there is a lower limit imposed by the design requirement of having a long, thin, flexible cable to allow reaching the remote target where the plasma is applied. In some embodiments of the present invention, it is potentially advantageous to extend the coaxial cable 203 beyond the length that imposes this lower limit. The introduction of C5 as a design degree of freedom also allows this. While the minimum practical value of the transformer inductance L5 remains a limitation for any given selected target resonant frequency f, it can still be much smaller in the decoupling transformer 305B than in the gain transformer 305A because the requirement for the primary inductance L4 to be smaller has been eliminated.

[0149] Third, at least if the second stage gain is chosen to be greater than one, frequency variations due to changes in load impedance may be reduced. For example, the impedance may change, causing damage. There is a potential advantage in reducing sensitivity to small fluctuations, while still retaining the automatic attenuation effect of large impedance changes. Even for a fixed load impedance, a manufacturing tolerance of a few percentage points (e.g., 10%) may be suitable for key electrical characteristics of the components, which may include the capacitance of the transmission line. This has the potential advantage of reducing the sensitivity of a resonant drive circuit to changes in, for example, the capacitance of the transmission line, while also retaining the advantages of a resonant circuit, such as self-stopping of high frequency signal generation when the transmission line is disconnected.

[0150] In a single-stage resonant generator, the capacitance of the transmission line is related to the frequency f∝(C coax ) -0.5 Directly related. Adding a second stage makes this relationship more complicated. In terms of the effect on frequency, the transmission line and the second stage together can be "seen" as an equivalent capacitor, making f∝(C equiv ) -0.5 Then, C equiv C coax The theoretical dependence of can be expressed in reverse as The effective gain of the second stage is M.

[0151] It can be understood that setting the gain M>1 will reduce the change in oscillation frequency due to (absolute) changes in load impedance. For simplicity, the above relationship omits ohmic elements (e.g., series resistors) that exist in actual systems. Taking this into account, the sensitivity to load impedance may increase.

[0152] Now briefly refer to Figure 3D , which shows in schematic form that C equiv C coax The theoretical dependence of is reduced. At the origin 361 there is zero transmission line capacitance; the effective capacitance is the baseline value, not necessarily zero.

[0153] The dependence of the effective capacitance on the transmission line capacitance decreases as the gain M increases. The details of this relationship will vary in actual circuits, for example, depending on the presence of other impedances such as parasitic impedances.

[0154] In system 300, if coaxial cable 203 is disconnected from the circuit, a resonant circuit will still exist on the primary side of the decoupling transformer. However, disconnection will also change the contribution of the decoupling transformer to the resonant circuit, which may result in a loss of high frequency power generation anyway.

[0155] When the coaxial cable 203 is reconnected, the effective resonance generated by both sides of the decoupling transformer together is still part of the load side of the circuit. This is true in a functional sense: if the circuits on both sides of the decoupling transformer are not allowed to resonate at mutually compatible frequencies, they cannot provide the frequencies required to allow the drive circuit 204 to perform its switching. The real (power dissipating) load circuit is still functioning to instruct the drive circuit, albeit through and in cooperation with the circuit driving the primary inductance of the decoupling transformer.

[0156] As described above, this effect decreases as the gain of the decoupling transformer increases. However, even in embodiments using gains above unity, the effects of impedance mismatch (e.g., due to damage to the coaxial cable 203) are unique. If the effect on the primary-side resonance of the decoupling transformer (despite the gain) is large enough, the same failure mode as before will result: loss of load resonance amplitude, loss of drive circuit synchronization, and ultimately reduced power or possible loss of power generation. If the impedance mismatch is not large enough to seriously reduce the resonance of the primary side of the decoupling converter, then the problem will cease: the drive circuit 204 will not see it. The load circuit remains in a fail-safe state.

[0157] Reference now Figure 3B , which schematically represents a flow chart of an operating method of a resonant high voltage plasma generating system according to some embodiments of the present invention.

[0158] At block 320, in some embodiments, the input voltage 202 is delivered to a power driver circuit (eg, including Figure 3A Block 204).

[0159] Figure 3B The operations of blocks 322 to 330 are presented in an order suitable for describing their interdependence (e.g., indicated by arrows); however, it should be understood that the operations in an actual device are arbitrarily interrelated, such that they may all develop simultaneously and / or at least partially react to each other as an aspect of the operation of the entire circuit. For example, in some embodiments, the feedback signal mentioned in block 322 is itself established due to the interaction of the electric field generated at the gain transformer and mentioned in block 326, and the interaction of the electric field generated at the gain transformer is in turn affected by the generation (block 328) and transmission (block 330) of the second-level AC voltage. Therefore, the effects of the operation of block 330 can be viewed as tracing back to the operation of block 322 to illustrate the interdependence of the events generated in the circuit. Therefore, there may be a situation where, if there is no feedback from block 322, the AC voltage will not be generated and transmitted at blocks 328, 330, but it can also be said that if there is no AC voltage, there will be no feedback.

[0160] At block 322 , in some embodiments, a feedback signal generated in response to activation of the power driver circuit is received from a load circuit including at least one transmission line (eg, coaxial cable 203 ) via at least gain transformer 305A.

[0161] At block 324, in some embodiments, the feedback signal entrains the drive circuit to oscillate, the oscillation being tuned (via the feedback signal) to the resonant frequency of the load circuit.

[0162] At block 326, in some embodiments, an AC voltage generated by the synchronized drive circuit is stepped up to a higher voltage via inductive coupling at a gain transformer 305 A. The higher voltage appears at the secondary (output) side of the gain transformer 305A in the first stage on the load circuit side of the overall power generation circuit.

[0163] At block 328, in some embodiments, the AC voltage on the first (primary / input) side of the decoupling transformer 305B induces a voltage on the second (secondary / output) side of the decoupling transformer 305B. In some embodiments, the gain at the decoupling transformer 305B is equal to or lower than the gain at the gain converter 305A. Optionally, the gain at the decoupling transformer 305B is about 1 (e.g., no gain). Optionally, the decoupling transformer 305B can be replaced by a decoupling coil 501 or another decoupling inductor configuration; for example, as described with respect to FIG. 5A to FIG. 5B Optionally, the gain of gain transformer 305A is at least 1.5, 2, 3, 4, 5 or more times smaller than the gain of gain transformer 305B.

[0164] At block 330, in some embodiments, the second voltage is transmitted along a transmission line (eg, coaxial cable 203 or other designed cables, such as twisted pair cables) to a plasma generation site and provides power for generating plasma.

[0165] High voltage generator with multiple transformer stages:

[0166] Reference now FIG. 4A to FIG. 4B , which schematically illustrates a resonant high voltage plasma generating system 400 according to some embodiments of the present invention. Figure 3A Compared with the block diagram, Figure 4A The generator 401 divides the decoupling transformer 305B into a plurality of decoupling transformers 405, where n≥2. Figure 4B405B, 405C, and 405D, driven by driver circuit 204 (including amplifier 308 having feedback input 307 and output 306). Although not all components other than substage 405B are shown, they can be understood to be repeated units of substage 405B with the connectivity shown. Substage 405C can be understood to represent one or more "intermediate" substages. Dosimetry can optionally be performed using dosimeter 505; for example, using Figure 2A One or more implementations described.

[0167] Dividing the decoupling transformer 305B into a plurality of decoupling transformers 405 summarizes Figure 3A and Figure 3C Although more complex, the multi-stage design has the potential advantage of distributing the voltage gain (if desired) beyond the practical range of a two-transformer design while maintaining a high operating (resonant) frequency.

[0168] Another potential advantage is reduced sensitivity to load impedance changes, summarized as:

[0169]

[0170] Where: M n is the nth transformer stage (n th transformer stage). However, it is best to pay attention to impedance matching to prevent signal reflections and harmonic distortion. It should be understood that each additional stage will reduce the overall efficiency, especially in practical systems that include resistive losses and parasitic capacitance.

[0171] In some embodiments, Figure 3B The method also applies to FIG. 4A to FIG. 4B The operation of the device is described in detail and modified as needed to account for a number of additional stages. For example, a suitable modification is to repeat the operation of block 328 between multiple decoupling stages as needed until a final decoupling stage is reached, at which the final AC voltage is transmitted through the transmission line to the plasma generation site to generate plasma.

[0172] In some embodiments, the transmission line (cable 203) itself is part of one or more intermediate stages, with one or more decoupling transformers positioned along the transmission line. This includes the option of dividing the cable 203 into multiple inductively coupled segments.

[0173] General:

[0174] As used herein, the term "about" with respect to quantities or values ​​means "within ± 10% of."

[0175] The terms "comprises", "comprising", "includes", "including" and their conjugations mean: "including but not limited to".

[0176] The term "consisting of" means: "including and limited to".

[0177] The term "consisting essentially of" means that the composition, method or structure may include additional ingredients, steps and / or parts, but only if these additional ingredients, steps and / or parts do not materially change the basic and novel characteristics of the claimed composition, method or structure.

[0178] As used herein, the singular forms "a", "an" and "the" include plural meanings unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

[0179] As used herein, the words "example" and "exemplary" mean "serving as an example, instance or illustration." Any embodiment described as "example" or "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features of other embodiments.

[0180] As used herein, the word “optionally” means “is provided in some embodiments and not provided in other embodiments.” Any particular embodiment of the present disclosure may include multiple “optional” features, unless such features conflict.

[0181] The term "method" as used herein means means, techniques, and procedures for accomplishing a given task, including but not limited to those known to practitioners in the fields of chemistry, pharmacology, biology, biochemistry, and medicine or readily developable from known means, means, techniques, and procedures.

[0182] As used herein, the term "treating" includes abrogating, substantially inhibiting, slowing or reversing the progression of a disorder, substantially ameliorating the clinical or aesthetic symptoms of a disorder, or substantially preventing the appearance of clinical or aesthetic symptoms of a disorder.

[0183] In various places of the present application, embodiments can be presented with reference to the range format. It should be understood that the description of the range format is only for convenience and brevity, and should not be interpreted as a rigid limitation on the scope of the present disclosure. Therefore, the description of the range should be deemed to have specifically disclosed all possible sub-ranges and each numerical value in the range. For example, a range description such as "from 1 to 6 (from 1 to 6)" should be considered to have specifically disclosed sub-ranges, such as "from 1 to 3 (from 1 to 3)", "from 1 to 4 (from 1 to 4)", "from 1 to 5 (from 1 to 5)", "from 2 to 4 (from 2 to 4)", "from 2 to 6 (from 2 to 6)", "from 3 to 6 (from 3 to 6)" and the like; and individual numbers in the range, such as 1, 2, 3, 4, 5 and 6. No matter how wide the scope is, this applies.

[0184] Whenever a numerical range is indicated herein (e.g., "10-15," "10 to 15," or any pair of numbers linked by these other such range indications), it is intended to include any number (fractional or integer) within the indicated range limits, including the range limits, unless the context clearly dictates otherwise. The phrases "range / ranging / ranges between" a first indicating number and a second indicating number and "range / ranging / ranges from" a first indicating number "to," "up to," "until," or "through" (or another such range indicating term) a second indicating number are used interchangeably herein and are intended to include the first and second indicating numbers and all fractions and integers therebetween.

[0185] Although the present disclosure is described in conjunction with specific embodiments, it is obvious that many substitutions, modifications and changes are obvious to those skilled in the art. Therefore, it is intended to cover all such substitutions, modifications and changes that fall within the spirit and broad scope of the appended claims.

[0186] It should be understood that, for the sake of clarity, certain features described in the context of separate embodiments in this disclosure may also be provided in combination in a single embodiment. Conversely, for the sake of brevity, various features described in the context of a single embodiment may also be provided separately or in any suitable subcombination or in any other described embodiment of the disclosure in a suitable manner. Certain features described in the context of various embodiments should not be considered essential features of those embodiments unless the embodiment would not function without those elements.

[0187] It is the intention of the applicant that all publications, patents and patent applications mentioned in this specification are incorporated herein by reference, just as each individual publication, patent or patent application is specifically and individually indicated to be incorporated herein by reference when cited. In addition, the citation or identification of any reference in this application should not be construed as an admission that the reference can serve as prior art for the present disclosure. To the extent that section headings are used, they should not be construed as necessary limitations. In addition, any priority document of the present application is hereby incorporated herein by reference in its entirety.

Claims

1. A power supply circuit for a non-thermal plasma generator, characterized in that: The circuit comprises: a gain transformer, comprising a primary coil and a secondary coil; a drive circuit electrically connected to drive current through the primary coil; a load circuit having a distal end and a proximal end, the distal end including a plasma generation site, the proximal end coupled to the secondary coil of the gain transformer; Wherein, the load circuit includes at least one decoupling transformer, and the at least one decoupling transformer inductively connects the plasma generating part and the secondary coil.

2. The power supply circuit according to claim 1, characterized in that: The load circuit has an impedance that determines a frequency at which the load circuit oscillates in response to current generated in the secondary coil.

3. The power supply circuit according to claim 2, characterized in that: The load circuit synchronizes the oscillation of the drive circuit.

4. The power supply circuit according to any one of claims 2 to 3, characterized in that: The oscillation of the load circuit is synchronized by feedback from the gain transformer.

5. The power supply circuit according to any one of claims 2 to 4, characterized in that: The frequency of the oscillation of the load circuit is high enough so that plasma generation at the plasma generation site is not extinguished within at least one complete oscillation cycle.

6. The power supply circuit according to any one of claims 1 to 5, characterized in that: The gain transformer provides a gain of at least 20.

7. The power supply circuit according to claim 6, characterized in that: The at least one decoupling transformer collectively provides a gain no greater than 1.

8. The power supply circuit according to any one of claims 1 to 7, characterized in that: The at least one decoupling transformer collectively provides a gain that is at least 2 times less than a gain provided by the gain transformer.

9. The power supply circuit according to any one of claims 1 to 8, characterized in that: The gain transformer and at least one coupling transformer include air or ferrite cores.

10. The power supply circuit according to any one of claims 1 to 9, characterized in that: The at least one decoupling transformer includes a plurality of decoupling transformers.

11. The power supply circuit according to any one of claims 1 to 10, characterized in that: The gain transformer and at least one coupling transformer isolate the plasma generation site from ground.

12. The power supply circuit according to any one of claims 1 to 11, characterized in that: The load circuit comprises: a transmission line, and A remote transformer of the at least one decoupling transformer comprises a secondary coil of the remote transformer, the secondary coil being inductively connected to a primary coil of the remote transformer and connected to a proximal side of the transmission line; The driving circuit: electrically connected to the proximal side of the transmission line through the primary coil and the secondary coil of the remote transformer, and providing an electrical signal having an operating frequency between 1 and 10 MHz to the transmission line, wherein the electrical signal is transmitted to a far end of the transmission line with an operating amplitude of at least 0.5 kV RMS; and The impedance of the secondary coil of the remote transformer combined with the capacitance of the transmission line is small enough so that a circuit portion including the transmission line and the secondary coil operates in a resonant manner when receiving the electrical signal.

13. The power supply circuit according to claim 12, characterized in that: The drive circuit stops generating the electric signal when the transmission line is disconnected, but keeps generating the electric signal when multiple values ​​of the capacitance of the transmission line vary within a range having at least a 10% difference between a minimum value and a maximum value thereof.

14. The power supply circuit according to any one of claims 12 to 13, characterized in that: The operating amplitude is at least 1 kV RMS.

15. The power supply circuit according to any one of claims 12 to 14, characterized in that: The transmission line is at least 50 cm long and is flexible.

16. The power supply circuit according to any one of claims 12 to 15, characterized in that: The load circuit provides a feedback signal to the driving circuit via a feedback network.

17. The power supply circuit according to claim 16, characterized in that: Oscillations of the load circuit synchronize the drive circuit via the feedback network to generate the electrical signal at the operating frequency.

18. A power supply circuit according to any one of claims 12 to 17, characterized in that: The power circuit is provided together with a gas supply chamber leading along the transmission line to the plasma generation site, the gas supply chamber and transmission line together forming components of a flexible probe with an overall diameter of less than 10 mm.

19. The power supply circuit according to any one of claims 12 to 18, characterized in that: The plasma generation site generates a non-thermal plasma when powered by the electrical signal.

20. A power supply circuit according to any one of claims 12 to 19, characterized in that: The at least one decoupling transformer together with the gain transformer constitutes a plurality of transformers connecting the proximal end of the transmission line to a low voltage signal oscillating at the operating frequency, wherein a voltage amplitude of the low voltage signal is at least 20 times smaller than the operating amplitude.

21. A power supply circuit according to any one of claims 12 to 20, characterized in that: The primary coil of the gain transformer has an inductance in the range of approximately 1 to 5 μH, and the secondary winding of the gain transformer has an inductance in the range of approximately 1000 to 5000 μH.

22. The power supply circuit according to claim 21, characterized in that: The gain transformer includes a feedback winding that provides a feedback signal to the drive circuit through a feedback network, and wherein the feedback winding has an inductance in the range of approximately 1 to 10 μH.

23. The power supply circuit according to claim 22, characterized in that: The feedback signal synchronizes the oscillation of the drive circuit to the operating frequency and is received at the feedback winding through the load circuit at the electrical oscillation frequency of the transmission line.

24. A power supply circuit according to any one of claims 12 to 23, characterized in that: The secondary winding of the remote transformer has an inductance in the range of approximately 20 to 80 μH, and the primary winding of the remote transformer has an inductance in the range of approximately 5 to 20 μH.

25. The power supply circuit according to claim 24, characterized in that: The secondary winding of the remote transformer is connected to a plurality of conductors of the transmission line through a plurality of electrical contacts.

26. The power supply circuit according to any one of claims 12 to 25, characterized in that: include: A pulse modulation circuit is operable to modulate the operating frequency at a lower frequency, wherein the lower frequency includes a frequency within a range of 0.1 to 1 KHz.

27. A method for decoupling gain and multiple frequency limits for non-thermal plasma generation, characterized in that: include: Providing an output electrical signal to a plasma generating region, the output electrical signal having an operating frequency and a voltage amplitude sufficient to generate plasma; Wherein, the plasma generation site is electrically connected to an input electrical signal oscillating at the operating frequency through at least two transformer stages, and the voltage of the input electrical signal is at least 20 times lower than the voltage of the output electrical signal.

28. The method according to claim 27, characterized in that: The voltage amplitude is at least 1 kV.

29. The method according to any one of claims 27 to 28, characterized in that: The operating frequency is between 1 and 10 MHz.

30. The method according to any one of claims 27 to 29, characterized in that: The plasma generating portion is connected to the input electrical signal through a transmission line, and the oscillation of the input electrical signal is synchronized by the oscillation of the circuit including the transmission line.

31. A non-thermal plasma generator, characterized in that: include: a gain transformer, comprising a primary coil and a secondary coil; a drive circuit electrically connected to drive a current through the primary coil; A load circuit having a distal end and a proximal end, the distal end including a plasma generation site for generating non-thermal plasma, the proximal end coupled to the secondary coil of the gain transformer; wherein the load circuit includes at least one decoupling inductor, the inductance provided includes an inductance connected in parallel with the secondary coil and an inductance connected in parallel with the plasma generation site.

32. The non-thermal plasma generator of claim 31, wherein: The load circuit has an impedance that determines a frequency at which the load circuit oscillates in response to current generated in the secondary coil.

33. The non-thermal plasma generator of claim 32, wherein: The load circuit synchronizes the oscillation of the drive circuit.

34. The non-thermal plasma generator of claim 33, wherein: The oscillation of the drive circuit is synchronized by feedback from the gain transformer.

35. A non-thermal plasma generator according to any one of claims 32 to 34, characterised in that: The frequency of the oscillation of the load circuit is high enough so that plasma generation at the plasma generation site is not extinguished within at least one complete oscillation cycle.

36. The non-thermal plasma generator according to any one of claims 32 to 35, characterized in that: include: A pulse modulation circuit is operable to modulate the frequency of the oscillation at a lower frequency in the range of 0.1 to 1 KHz.

37. The non-thermal plasma generator according to any one of claims 31 to 36, characterized in that: The gain transformer provides a gain of at least 20.

38. The non-thermal plasma generator of claim 37, wherein: The at least one decoupling inductor includes at least one decoupling transformer, and the at least one decoupling transformer collectively provides a gain no greater than 1.

39. The non-thermal plasma generator according to any one of claims 31 to 38, characterized in that: The at least one decoupling inductor includes a plurality of decoupling transformers, the plurality of decoupling transformers collectively providing a gain that is at least 2 times less than a gain provided by the gain transformer.

40. The non-thermal plasma generator according to any one of claims 31 to 39, characterized in that: The gain transformer includes an air or ferrite core.

41. The non-thermal plasma generator according to any one of claims 31 to 40, characterized in that: The at least one decoupling inductor includes a plurality of decoupling transformers.

42. The non-thermal plasma generator according to any one of claims 31 to 41, characterized in that: The at least one decoupling inductor includes an inductor coil connected in parallel to the secondary coil and in parallel to the plasma generation site.

43. The non-thermal plasma generator of claim 32, wherein: The drive circuit stops oscillating when the plasma generation site is disconnected from the load circuit, but keeps oscillating when multiple values ​​of the frequency of oscillation of the load circuit vary within a range having at least a 1000% difference between a minimum value and a maximum value of the range.

44. The non-thermal plasma generator according to any one of claims 31 to 43, characterized in that: When current is driven through the primary coil of the gain transformer, an operating voltage amplitude of at least 1 kV RMS is generated at the plasma generation region.

45. A non-thermal plasma generator according to any one of claims 31 to 44, characterised in that: A transmission line is included, the transmission line connecting the plasma generation site and the at least one decoupling inductor; wherein the transmission line is at least 50 cm long and is flexible.

46. ​​The non-thermal plasma generator of claim 45, wherein: A gas supply chamber is provided along the transmission line leading to the plasma generation site, the gas supply chamber and transmission line together forming components of a flexible probe having an overall diameter of less than 10 mm.

47. The non-thermal plasma generator of claim 44, wherein: The at least one decoupling inductor together with the gain transformer constitutes one or more transformers, which transmit the operating voltage to the plasma generation region, wherein the plasma generation region has an amplitude at least 20 times greater than the voltage amplitude in the primary coil of the gain transformer.

48. A non-thermal plasma generator according to any one of claims 31 to 47, characterised in that: The primary coil of the gain transformer has an inductance in the range of approximately 1 to 5 μH, and the secondary coil of the gain transformer has an inductance in the range of approximately 1000 to 5000 μH.

49. The non-thermal plasma generator of claim 34, wherein: Feedback from the gain transformer is provided by a feedback winding of the gain transformer, and wherein the feedback winding has an inductance in the range of approximately 1 to 10 μH.

50. A non-thermal plasma generator according to any one of claims 31 to 49, characterised in that: The at least one decoupling inductor includes at least one decoupling transformer, and a remote side coil of the at least one decoupling transformer has an inductance in the range of approximately 20 to 80 μH, and the remote side coil is a coil of a remote decoupling transformer of the at least one decoupling transformer having a primary coil, and the primary coil has an inductance in the range of approximately 5 to 20 μH.

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