Power Draw of DPF devices

[rimmini]

What is the typical power input (kVA) for a DPF device?

[Francisl]

rimmini wrote: What is the typical power input (kVA) for a DPF device?

There is no typical DPF device. They range in size from small tabletop units for training college physics students to very large machines for research purposes. So far no one has indicated that they have produced more power than they have used to operate their device.

[rimmini]

Thank you. Is there a formula for figuring out the required of a device based on its size? I assume the parameters will be related to the interelectrode potential and the magnetic flux of the field. ( I tried to write some extremely rough draft equation but the forum does not appear to use MathJax.)

[Francisl]

rimmini wrote: Thank you. Is there a formula for figuring out the required of a device based on its size? I assume the parameters will be related to the interelectrode potential and the magnetic flux of the field. ( I tried to write some extremely rough draft equation but the forum does not appear to use MathJax.)

Look for posts by asymmetric_implosion on this website. He is an expert in the information that you are looking for. He has participated in a lot of the technical discussions.

[asymmetric_implosion]

The short history of the PF: The main objective of PF devices early in their history was to produce large bursts of radiation. It was initially believed that could reach fusion gain conditions. However, the bumps on the road cropped up quickly when devices were scaled up to a few MA current levels. The typical characteristics of a plasma focus are:
1) a low repetition rate device firing a few shots per hour.
2) Cathode radius is 2-3X the anode radius.
3) Operating pressures between 1 Torr and 10 Torr.
4) Simple RLC circuit to drive the system.
5) charge voltage of ~20 kV on the capacitor.

Plasma focus devices have been built that are high repetition rate, high pressure or lower/higher charge voltage.

The information you are seeking depends highly on the design. Typically you iterate on the design when you have some goals in mind. Typical goals are the radiation yield of the system, the system inductance, the charge voltage and the repetition rate. I believe all other criteria are derivatives of these inputs. Typical scaling of the device depends upon the radiation yield (Y) proportional to the current to a power. Y=a*I^n. n is typically around 4 but varies from 3 to 5. The proportionality constant a can vary widely. I don’t believe ‘a’ is truly a constant but that is a story for another time. When you know the yield and derive ‘a’ and ‘n’ from others work, the peak current is known. With a peak current, you can use models to estimate the capacitance knowing the target inductance and charge voltage. The physical size of the system is largely driven by the capacitors and the inductance. The electrode design is driven by the rise time of the current pulse which is driven by the capacitance and inductance. The repetition rate drives the wall plug power (kVA) to power an instrument and the parts selection. Do you want a capacitor that survives a few days or a few years. The electrode material and thermal management are driven by the total power into the system. Single shot machines seldom thermally manage the electrodes or vacuum chamber. Repetition rate systems typically challenge the thermal management systems on the W/cm^2 basis. Electrodes tend to be small and they tend to get hot relative to the power input. This is typically the point when one starts to iterate seriously. Some experiments might feed into the iterations. If you want to design a machine, best of luck. I think you will find the folks that operate machines are generally very helpful and supportive.

[Author]

Posts