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.