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BIPOLAR MARX GENERATOR Martin Sack, René Stängle Forschungszentrum
Karlsruhe GmbH, Institute
for Pulsed Power and Microwave Technology For the
industrial electroporation of plant cells it is of advantage to set up the
electroporation reactor in a bipolar configuration, /1/. With the electrodes
pulsed simultaneously with the same voltage of opposite polarity, in order to
achieve the same electric field strength, less effort for the insulation to
ground is necessary than for an unipolar reactor. The required voltage can be
delivered by a bipolar Marx generator. For a
reliable operation of such a configuration, the way the generator and the
load are grounded is essential. To prevent the power supply from an
over-voltage in the case of an undesired flash-over inside the
electroporation reactor, a good ground connection at the center of the
generator keeps the potential at the supply clamps low. But this measure has
an influence on the coupling of the two sides of the generator during the
switching process and might require an additional capacitive coupling path. A
transient insulation to ground by means of a coil fosters a better switching
behavior, but in the case of a flash-over the generator potential may float
resulting in an over-voltage. Here, an additional over-voltage protection for
the power-supply is required. In the work the different approaches for the
ground connection are discussed. 1. M. Sack, C. Schultheiss, and H. Bluhm:
“Triggered Marx Generators for the Industrial-Scale Electroporation of Sugar
Beets”, IEEE Trans. Industry Applications, 2005, pp. 725-733. |