DE202021002118U1 - A device that generates a diffuse, low temperature, non-equilibrium plasma - Google Patents

Abstract

the device for generating a diffuse low-temperature non-equilibrium plasma differs in that the generator of the high-voltage pulses of nanosecond duration is placed in the handpiece and in the immediate vicinity of the location of the plasma generation.

Description

The invention relates to a device for plasma treatment of biological objects. Basics

If a sufficiently high voltage is applied between two electrodes, the gas between the electrodes is ionized and a plasma is created.
A plasma contains numerous reactive species such as ions and electrons, but also molecules or atoms in different excited states and radicals.

Due to their lower mass, the electrons are accelerated faster in the electric field than the heavier ions. By colliding with the surrounding gas molecules, the electrons give their energy back to the respective collision partner.

If the energy of the electron is small, an elastic collision occurs. The energy exchange is very small because of the low mass of the electron and the electron is only deflected. If the energy of an electron is greater than the respective excitation, dissociation or ionization energy, this energy can be transferred to a gas molecule through an inelastic collision.

If the particle density is low or the electric field is large enough, the kinetic energy of the electrons will on average be greater than the kinetic energy of the gas molecules. In this case one speaks of a non-equilibrium plasma.

The proposed device for generating diffuse, low-temperature, non-equilibrium plasma with a temperature comparable to that of the human body can find use in medicine.

Cold non-equilibrium plasma jets at atmospheric pressure have recently received a lot of attention. Plasma devices generate a jet of cold plasma in free space (ambient air), not only in limited discharge gaps. So they can be used for direct treatment and there are no restrictions on the size of the objects to be treated.

State of the art

Examples of common devices with non-equilibrium plasma jets at atmospheric pressure are: devices with non-equilibrium plasma jets with alternating current, radio frequency, microwave and pulsed direct current.

The pulsed DC power supply provides a current with a single polarity and variable voltage. This rectified waveform is generated with either a half-wave or a full-wave rectifier.

Well-known handheld portable devices that generate low temperature plasma at atmospheric pressure ( EP0837622 ), use gas mixtures of air with nitrogen or helium as plasma sources, and high-voltage discharge as ionization with strict requirements on the pulse amplitude.

A device is known ( US 2013/0072861 ), which generates cold non-equilibrium plasma and was manufactured as a hand-held device for the treatment of living tissue. This device uses in its construction a complicated system of ionization of working gases with high voltage, which is achieved by a high voltage transformer and a system of resonance circuits with magnetic fields.

A device is also known ( U.S. 9,999,452 ) that a cold plasma jet is generated from the working gas (helium) and used as a surgical tool. The cold plasma jet is generated with the help of a high voltage transformer on a ferrite core.

Materials for making a compact device for generating cold plasma using a piezo transformer with low power consumption have been published.

A device is known for generating a cold non-equilibrium plasma that ionizes the working gas helium or argon by high-frequency high-voltage pulses that are generated in the base unit and enter the hand-held device via a coaxial cable.

Prototypes of the proposed device can adopt the devices described in and. The disadvantage of the devices described is that a high-voltage nanosecond pulse is fed into the device via a special external coaxial cable and, in the device described in, the high voltage received directly in a hand-held device takes the form of a sine wave with a rising increase in the order of ten Has microseconds.

With the method described, it is not possible to get short high voltage nanosecond voltage pulses in this device.

The use of unipolar high voltage nanosecond pulses with an amplitude of about 6-10 kV and a rise time in the The order of magnitude of 2-5 nanoseconds and a duration of 50-70 nanoseconds makes it possible to obtain a completely diffuse (homogeneous) cold plasma.

Due to the short rise time of the high voltage pulse, the electrons and ions in the plasma do not have time to warm up, but the electrons gain more speed, which contributes to the further ionization of the gas.

The main problem with the design of hand-held cold plasma tools is that the high voltage required for ionization must be supplied from external devices either through special high voltage lines or a special cable in the case of pulsed signals.

As a rule, the high voltage required for ionization is in the range of 5kV to 30kV (depending on the design of the discharge electrodes).

To generate a completely homogeneous (diffuse) cold plasma, the high-voltage ionization voltage in the form of a direct current pulse with a rise time up to an amplitude of 6-10 kV should not be more than 10 ns. It is a problem to pass nanosecond pulses with such declared properties through cables. It is mainly due to the inherent capacitance of the coaxial cable.

Existing high-voltage coaxial cables have an inherent capacitance of around 100 pF per meter. Assuming that the working device is to be connected to the base unit with a cable at least 1.8-2 meters long (for the convenience of treating biological surfaces), then the capacitance over this length is about 150-200pF, which is the High voltage nanosecond pulse would completely extinguish.

There are special circuit devices and also special coaxial cables, but these are exotic and quite complicated technical solutions that are not justified even for small series production.

Troubleshooting

In the presented invention it was possible for the first time to build a high-voltage nanosecond pulse generator directly into the housing of a portable cold plasma handpiece.

This made it possible to avoid complex solutions for the transmission of the nanosecond pulse from the shaping unit via cables.
The nanosecond high-voltage pulse is generated directly at the ionization point of the gas, creating a homogeneous, diffuse cold plasma beam. The nanosecond shaper is based on an energy storage device (inductive) and a silicon high-voltage disconnector.

DSRD (drift step recovery diodes) are used as high-voltage disconnectors. In contrast to the usual circuit solutions for high-voltage nanosecond pulse formers on DSRD elements, the load for DSRD elements is shifted to the control unit in the present invention, and only the memory unit and a silicon high-voltage disconnector remain in the handpiece of the device.

This enabled a drastically simplified design of the nanosecond pulse shaper and a more cost-effective application of the plasma generated by high-voltage nanosecond pulses. This structure enables the formation of individual and packets of nanosecond pulses with a frequency of 1Hz to 50kHz.

• - Kaltplasma-Handstück (ist in 1 dargestellt)
• - Das Steuereinheit ist schematisch in 2. dargestellt
• - Einheit zur Bildung des Gasgemisches
• - Das Steuereinheit enthält:
• - externes Bedienfeld 13 (2), einschließlich einer Betriebsanzeige und Bedienelementen zur Steuerung der Modi der Bildung des kalten Plasmastrahls
• - Mikroprozessorsteuerung 14 (2),
• - Nanosekunden-Impulsgeber 15 (2),
• - Spannungsversorgung 16 (2),
• - dreipolige Elektromagnet-Steuereinheit 17 (2) ,.

The device consists of 3 main units:

• - Cold plasma handpiece (is in 1 shown)
• - The control unit is schematically in 2 . shown
• - Unit for forming the gas mixture
• - The control unit contains:
• - external control panel 13th ( 2 ), including an operating display and controls for controlling the modes of formation of the cold plasma jet
• - microprocessor control 14th ( 2 ),
• - Nanosecond pulse generator 15th ( 2 ),
• - power supply 16 ( 2 ),
• - three-pole solenoid control unit 17th ( 2 ),.

• - Arbeitsgasflasche (He, Ar) 18 (2),
• - Gasmischer 19 (2),
• - Drossel 20 (2),
• - Verdichter 21 (2),

The unit for forming the gas mixture contains:

• - Working gas cylinder (He, Ar) 18 ( 2 ),
• - gas mixer 19th ( 2 ),
• - throttle 20th ( 2 ),
• - Compressor 21 ( 2 ),

• - ein dielektrisches Gehäuse 1(1) in dessen Innerem sich befinden:
• - Energiespeicher 2(1,2)
• - dielektrische Ringe 3 (1,2) mit Bohrungen für den Arbeitsgasdurchlass
• - gemeinsame Masseklemme 4(1,2) und Triggerimpuls-Versorgungsklemme 11(1,2) vom Nanosekunden-Impulsgeber 15 (2) der externen elektronischen Steuereinheit
• - Silizium-Hochspannungsschalter 5(1,2)
• - Hochspannungselektrode 6((1,2))
• - zentrierender dielektrischer Ring 7((1,2)) mit Kanälen für den Gasdurchgang
• - Hochspannungsionisationselektrode 8 ((1,2)) aus Edelstahl, in der ein Keramikeinsatz mit einer Spitze aus Titandioxid zur Erhöhung der Produktion von OH-Radikalen montiert ist
• - Quarzrohr 9((1,2)) (Düse) für kalte Plasmastrombildung
• - Ionisationskammer 10(1,2), in der das einströmende Gas (Helium, Argon, Stickstoff, Luft oder Mischungen dieser Gase), das aus dem Gasmischer 19(2) der Einheit zur Bildung des Gasgemisches kommt, durch einen Hochspannungs-Nanosekundenimpuls ionisiert wird, der an der lonisationselektrode 8 (1,2) gebildet wird
• - einem dreipoligen Elektromagneten 12(2) der um die Düse 9 herum angeordnet ist, um die Rotation des Plasmastrahls zu realisieren, der einen vollen Kegel bildet, um einen breiteren Bereich des Plasmastrahleffekts zu schaffen. Die Elektromagnetspitzen bilden ein magnetisches Wechselfeld quer zum Plasmastrahl.

The handpiece has

• - a dielectric housing 1 ( 1 ) inside of which are:
• - Energy storage 2 ( 1 , 2 )
• - dielectric rings 3 ( 1 , 2 ) with holes for the working gas passage
• - common earth terminal 4 ( 1 , 2 ) and trigger pulse supply terminal 11 ( 1 , 2 ) from the nanosecond pulse generator 15th ( 2 ) the external electronic control unit
• - Silicon high-voltage switch 5 ( 1 , 2 )
• - high voltage electrode 6 (( 1 , 2 ))
• - centering dielectric ring 7 (( 1 , 2 )) with channels for gas passage
• - high voltage ionization electrode 8th (( 1 , 2 )) made of stainless steel, in which a ceramic insert with a tip made of titanium dioxide is mounted to increase the production of OH radicals
• - quartz tube 9 (( 1 , 2 )) (Nozzle) for cold plasma flow generation
• - ionization chamber 10 ( 1 , 2 ), in which the inflowing gas (helium, argon, nitrogen, air or mixtures of these gases) coming out of the gas mixer 19 ( 2 ) the unit for the formation of the gas mixture comes, is ionized by a high-voltage nanosecond pulse, which is applied to the ionization electrode 8 ( 1 , 2 ) is formed
• - a three-pole electromagnet 12 ( 2 ) around the nozzle 9 arranged around to realize the rotation of the plasma jet forming a full cone to create a wider area of the plasma jet effect. The electromagnetic tips form an alternating magnetic field across the plasma jet.

Description of the device.

The handpiece of the device consists of a dielectric housing 1 ( 1 , 2 ) and the energy storage unit is located inside the housing 2 ( 1 , 2 ), load-bearing dielectric rings 3 ( 1 , 2 ) with holes for the passage of the working gas, a common earth terminal 4th ( 1 , 2 ) and a terminal for the supply of trigger pulses 11 ( 1 , 2 ) from an external unit, a silicon high-voltage disconnector 5 (( 1Fig .2)), a high voltage electrode 6 ( 1 , 2 ), a centering dielectric ring 7 ( 1 , 2 ) with gas passages, a high-voltage ionization electrode 8th ( 1 , 2 ) made of stainless steel, a quartz tube for the formation of a cold plasma flow, an ionization chamber 10 , ( 1 , 2 ) in which the inflowing gas (helium, argon, nitrogen, air or their mixtures) is ionized by a high-voltage nanosecond pulse that is applied to the ionization electrode 8 ( 1 , 2 ) forms.

When a trigger pulse is received at electrode 1l ( 1 , 2 ) from the external unit accumulates the inductive storage 2 ( 1 , 2 ) during the duration of the trigger pulse energy. After the trigger pulse, the silicon DSRD high-voltage disconnector switches the memory to the ionization electrode within 2-5 nanoseconds.

The ones in memory 2 ( 1 , 2 ) Stored energy is converted at the ionization electrode into a high-voltage pulse of nanosecond duration with a rise time of up to 2.5 kV / ns.

To prepare the device for operation, a working gas mixture of helium (or argon) and air is formed in order to increase the production of active OH radicals. For this purpose, a metered air mixture is used in the working gas compressor 21 ( 2 ) through the adjustable throttle 20th ( 2 ) which prevents the working gas from being pressurized by the air mixture.

The gas mixture is in the gas mixer 19th formed the gas from the source 18th ( 2 ) and air from the compressor 21 ( 2 ) receives.

• - Plasmaleistung
• - Temperatur des Plasmastrahls
• - Behandlungszeit
• - Arbeitsgasstand im Ballon
• - Durchflussmenge des Gasgemisches, etc.

When the device is connected to the mains (220 V mains), the power supply unit 16 ( 2 ) the necessary supply voltages for the external control panel 13 ( 2 ), the microprocessor controller 14th ( 2 ) and the nanosecond pulse generator 15 ( 2 ). The control and display elements on the control panel 13 ( 2 ) allow the setting and monitoring of the parameters of the cold plasma jet formation and the operating status of the device,
including:

• - plasma power
• - temperature of the plasma jet
• - treatment time
• - Working gas level in the balloon
• - Flow rate of the gas mixture, etc.

The microprocessor control 14th ( 2 ) ensures that the preset mode of cold plasma jet formation is maintained and the necessary control signals are output to the nanosecond pulse generator 15th ( 2 ) and the three-pole electromagnet control unit 17 ( 2 ).

When the trigger pulse from the nanosecond pulser 15th ( 2 ) on the electrode 11 ( 1 , 2 ) of the portable cold plasma tool arrives, the inductive memory stores 2 ( 1 , 2 ) energy for the duration of the trigger pulse.

After completion of the trigger impulse action, the silicon DSRD switch switches the memory to the ionization electrode within 2-5 nanoseconds. The ones in memory 2 ( 1 , 2 ) stored energy is converted into a high-voltage pulse with a duration of nanoseconds with a rise time of up to 2.5kV / ns at the ionization electrode 8 ( 1 , 2 ) converted.

The use of a built-in nanosecond shaper of high voltage pulses in a portable plasma emitter made it possible to achieve a plasma spot diameter of up to 10 mm, thereby removing most of the limitations in treating large damaged areas of biological tissue.

By generating pulses in the nanosecond range directly in the ionization chamber, it was possible to increase the yield of reactive particles generated by the plasma (RNS, RONS) to create a cold non-equilibrium plasma in contrast to the methods mentioned above and to maintain its use in medicine.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 0837622 [0010]
• US 2013/0072861 [0011]
• US 9999452 [0012]

Claims (15)

the device for generating a diffuse low-temperature non-equilibrium plasma differs in that the generator of the high-voltage pulses of nanosecond duration is placed in the handpiece and in the immediate vicinity of the location of the plasma generation. the apparatus for generating a diffuse, low-temperature, non-equilibrium plasma differs in that it contains a microprocessor controller for automatically controlling the process of plasma flow formation. the device for generating a diffuse low-temperature non-equilibrium plasma, characterized in that the microprocessor control comprises a generator module of the control signals and a polyphase electromagnet. the device for generating a diffuse low-temperature non-equilibrium plasma, characterized in that it contains a microprocessor control for automatic control of the process of plasma formation. the device for generating a diffuse low-temperature non-equilibrium plasma, characterized in that the handpiece contains a generator for generating pulses of nanosecond duration. the working tool after Claim 5 has a nanosecond pulse generator that contains an inductive energy store and a nanosecond circuit breaker based on an SOS or DSRD diode. the handpiece Claim 5 contains a multi-phase electromagnet which is arranged in the nozzle outlet area of the handpiece. the device for generating a diffuse low-temperature non-equilibrium plasma is characterized in that the handpiece contains a polyphase electromagnet for controlling the dynamic properties of the arc, which contains a 3-phase winding for controlling the spatial position of the plasma jet. the device differs in that it contains a regulator of the parameters of the gas mixture and a compressor for generating the flow of the gas mixture. the apparatus for generating a diffuse, low-temperature, non-equilibrium plasma is characterized in that it contains a regulator for the composition of the gas mixture in order to control the velocity of the gas mixture. the device for generating a diffuse low-temperature non-equilibrium plasma is characterized in that the regulator of the composition of the gas mixture contains elements for controlling the rate of the gas mixture. the device for generating a diffuse low-temperature non-equilibrium plasma is characterized in that the regulator of the composition of the gas mixture contains elements for controlling the output frequency of the gas mixture. the device for generating a diffuse low-temperature non-equilibrium plasma is characterized in that the handpiece contains an ionization electrode with a tip which can be coated with either titanium dioxide, silver or gold. the device for generating a diffuse low-temperature non-equilibrium plasma is characterized in that the handpiece contains a device for changing the length of the working part. the device for generating a diffuse low-temperature non-equilibrium plasma is characterized in that the handpiece contains a device for positioning a light mark on the point of plasma action.

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