EMC Question of the Week: July 11, 2022

IEMI source hidden in a briefcase in a control center

Which of the following is often employed in sources of intentional electromagnetic interference (IEMI)? 

  1. Marx generator
  2. Van de Graaff generator
  3. Tesla coil
  4. Flux capacitor


The best answer is “a.” A Marx generator (first developed by Erwin Otto Marx in 1924) efficiently converts stored electrical energy into a high-voltage pulse. It generates the pulse by charging a number of capacitors in parallel, then suddenly connecting them in series. Marx generators have been employed by several commercial and amateur IEMI devices.

IEMI is a significant concern for electronic products and systems that play an essential role in protecting people and property. There have been many documented cases of IEMI attacks on banking systems, gaming systems, communications systems, and security systems. Automotive, aerospace and robotic systems are also potentially vulnerable.

While almost any source of electromagnetic energy could potentially be used to generate electromagnetic interference in the right circumstances, IEMI sources tend to favor compact, portable designs. Like Marx generators, Van de Graaff generators can also produce electrical pulses, but they rely on triboelectric charging and tend to be pretty large for a given energy level. Tesla coils can generate significant interference, but they are not particularly efficient or compact.

And flux capacitors??  A flux capacitor is a fictional device that facilitated time travel in the 1985 movie, "Back to the Future." It's not currently a component in any IEMI devices that we are aware of. 

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