Disclosed is a plasma torch with a structure capable of performing reversed polarity/straight polarity operation, wherein the plasma torch is coupled to a melter and melts a waste material such as radioactive waste or industrial waste by generating and sustaining a plasma arc between electrodes, the plasma torch including: a rear electrode provided inside a torch pipe and electrically connected to become one of an anode and a cathode; and a front electrode provided at a front end of the torch pipe at a position adjacent to a front end of the rear electrode and electrically connected to become a remaining one of the anode and the cathode, wherein electrical connections of the rear and front electrodes are switchable with each other so that the plasma torch operates as a reversed polarity plasma torch or a straight polarity plasma torch.

Disclosed is a plasma torch with a structure capable of performing reversed polarity/straight polarity operation, wherein the plasma torch is coupled to a melter and melts a waste material such as radioactive waste or industrial waste by generating and sustaining a plasma arc between electrodes, the plasma torch including: a rear electrode provided inside a torch pipe and electrically connected to become one of an anode and a cathode; and a front electrode provided at a front end of the torch pipe at a position adjacent to a front end of the rear electrode and electrically connected to become a remaining one of the anode and the cathode, wherein electrical connections of the rear and front electrodes are switchable with each other so that the plasma torch operates as a reversed polarity plasma torch or a straight polarity plasma torch.

A system for determining an operational state of an atmospheric pressure plasma. The system has a transformer for coupling power into the atmospheric pressure plasma, a current sampling circuit configured to sample at least one current pulse flowing through a primary winding of the transformer, and a programmed microprocessor configured to determine, from a waveform of the current pulse, the operational state of the atmospheric pressure plasma. The operational state is one of: a no plasma state, a plasma origination state indicative of an ignited arc expanding into a plasma by gas flow thereinto, and a plasma maintenance state indicative of the plasma being expanded.

A system for determining an operational state of an atmospheric pressure plasma. The system has a transformer for coupling power into the atmospheric pressure plasma, a current sampling circuit configured to sample at least one current pulse flowing through a primary winding of the transformer, and a programmed microprocessor configured to determine, from a waveform of the current pulse, the operational state of the atmospheric pressure plasma. The operational state is one of: a no plasma state, a plasma origination state indicative of an ignited arc expanding into a plasma by gas flow thereinto, and a plasma maintenance state indicative of the plasma being expanded.

A method and apparatus for operating a DC plasma torch. The power supply used is at least two times the average operating voltage used, resulting in a more stable operation of the torch. The torch can include two concentric cylinder electrodes, the electrodes can be graphite, and the plasma forming gas can be hydrogen. The power supply provided also has the capability of igniting the torch at a pulse voltage of at least 20 kilovolts.

A method and apparatus for operating a DC plasma torch. The power supply used is at least two times the average operating voltage used, resulting in a more stable operation of the torch. The torch can include two concentric cylinder electrodes, the electrodes can be graphite, and the plasma forming gas can be hydrogen. The power supply provided also has the capability of igniting the torch at a pulse voltage of at least 20 kilovolts.

The object of the present disclosure is to efficiently generate plasma. In the plasma device of the present disclosure, a dielectric barrier discharger and an arc discharger are included, but the arc discharger is provided downstream from the dielectric barrier discharger in a discharge space where a gas for generating plasma is supplied. Dielectric barrier discharge occurs at the dielectric barrier discharger, and arch discharge occurs at the arc discharger. As a result of the gas for generating plasma being activated in the dielectric barrier discharge, the aforementioned gas can be adequately converted to plasma in the arc discharger.

The object of the present disclosure is to efficiently generate plasma. In the plasma device of the present disclosure, a dielectric barrier discharger and an arc discharger are included, but the arc discharger is provided downstream from the dielectric barrier discharger in a discharge space where a gas for generating plasma is supplied. Dielectric barrier discharge occurs at the dielectric barrier discharger, and arch discharge occurs at the arc discharger. As a result of the gas for generating plasma being activated in the dielectric barrier discharge, the aforementioned gas can be adequately converted to plasma in the arc discharger.

This invention concerns power supplies suitable for electric arc gas heaters such a plasma torches. It more particularly relates to the dimensioning of the inductor in the switched-mode DC to DC converter used for feeding the torch. The invention concerns in particular a DC power supply for driving a non-transferred electric arc gas heater, comprising: an AC to DC rectifier providing a potential U.sub.0; a DC to DC switching converter having a switching frequency f.sub.s; a current control loop having a latency ; and, a ballast inductor having an inductance L; characterized in that inductance L is such that

[00001]$L>\left(\frac{U_0}{1.Math.5.Math.0.Math.0}\right).Math.,\mathrm{and}.Math..Math.L<\frac{1}{f_s}.Math.\left(\frac{U_0}{2.Math.0.Math.0}\right).$

Such a design ensures the stability of the current control loop, while also ensuring a sufficient amount of current ripple to spread out the erosion zone on the electrodes of the torch.

This invention concerns power supplies suitable for electric arc gas heaters such a plasma torches. It more particularly relates to the dimensioning of the inductor in the switched-mode DC to DC converter used for feeding the torch. The invention concerns in particular a DC power supply for driving a non-transferred electric arc gas heater, comprising: an AC to DC rectifier providing a potential U.sub.0; a DC to DC switching converter having a switching frequency f.sub.s; a current control loop having a latency ; and, a ballast inductor having an inductance L; characterized in that inductance L is such that

[00001]$L>\left(\frac{U_0}{1.Math.5.Math.0.Math.0}\right).Math.,\mathrm{and}.Math..Math.L<\frac{1}{f_s}.Math.\left(\frac{U_0}{2.Math.0.Math.0}\right).$

Such a design ensures the stability of the current control loop, while also ensuring a sufficient amount of current ripple to spread out the erosion zone on the electrodes of the torch.