Patent ID: 8025775

Claim:
A plasma treatment arrangement for treating a workpiece, the arrangement comprising: a vacuum process chamber ( 2 ) for receiving workpieces and for containing a plasma discharge for treating the workpieces, the chamber having two electrodes ( 3 ) that are spaced from each other in the chamber with the plasma discharge between the electrodes; and a vacuum plasma generator with two outputs ( 26 , 26 ′) that are directly connected respectively to the two electrodes ( 3 ) for feeding a plasma discharge for the treatment of workpieces in the vacuum chamber, the generator comprising: a converter ( 7 ) having a DC voltage output, a DC input, a control input ( 7 a ) and a converter transformer ( 17 ) for at least one of setting and regulating an output DC voltage of the converter as a low-level and as a high-level setter for adjusting the DC voltage output to be an adjustable DC voltage, a mains connection ( 6 a ) for the junction to an AC voltage mains, a mains rectifier ( 6 ) connected to the mains connection ( 6 a ) and connected to the DC input of the converter ( 7 ), and a controlled full bridge circuit ( 13 ) connected to the converter DC voltage output, the bridge circuit having the two outputs ( 26 , 26 ′) that are each a potential-free generator output ( 26 , 26 ′), which transposes the adjustable DC voltage output of the converter into pulses of 1 to 500 kHz, and, in the bridge circuit ( 13 ) a potential-isolating transformer ( 14 ) is included for galvanic decoupling of the generator outputs ( 26 , 26 ′), the converter transformer ( 17 ) located upstream of the potential-isolating transformer ( 14 ) in the vacuum plasma generator so that the potential-isolating transformer ( 14 ) is located downstream of the converter transformer ( 17 ) in the generator, the potential-isolating transformer ( 14 ) having at least one primary winding connected to the bridge circuit and at least one secondary winding having two connections, the two connections consist only of respective lines from the secondary winding being respectively and directly connected by said respective lines only to the two outputs ( 26 , 26 ′) which are respectively and directly connected only by said lines to the two electrodes ( 3 ) to short circuit the electrodes via the secondary winding and for galvanic decoupling of the two outputs so that a bipolar voltage at the secondary winding of the potential-isolating transformer is transferred to the electrodes so that the electrodes operated with alternating polarity so that one electrode operates as a cathode while the other electrode operated as an anode in a periodically alternating fashion for inhibiting charges on surfaces of the electrodes caused by reversing of polarity at the electrodes and for the creating of short circuiting of the electrodes during repeated zero crossings of the bipolar voltage, a voltage transformation ratio of the bridge circuit ( 13 ) with the potential-isolating transformer ( 14 ) being maximally 1:2.