A pumping apparatus includes a housing having an inlet at a first end and an outlet at an opposite second end. According to the invention, cutout are arranged in the electrically insulating material, via which the second side of each metal web is accessible for a voltage or current measurement apparatus. The gate material stack includes a semiconductive gate material. In this way, high grade polysilicon is produced without a metallurgical grade silicon precursor and the process these processes consumes the byproducts in a continuous manner madding it less expensive than traditional methods of producing polysilicon and more environmentally friendly.