The mysterious plague suffered by U.S. embassy staff and CIA officials in Cuba, China, Russia and other countries over the past four years appears to have been caused by high-powered microwaves, according to a report released by the National Academy. A committee of 19 experts in medicine and other fields concluded that pulsed radiofrequency energy is the “most credible mechanism” for explaining the disease, known as Havana syndrome.
The report does not clarify who the embassies were or why they were run. But the technology behind the alleged weapons is well understood and is part of the Cold War arms race between the US and the Soviet Union. High-power microwave weapons are generally designed to disable electronic equipment. But as reports from Havana Syndrome show, these energy pulses can also harm people.
As an electrical and computer engineer who designs and builds high-power microwave sources, I have spent decades studying the physics of these sources, including work with the U.S. Department of Defense. Energy-directed microwave weapons convert radiated electromagnetic energy from an energy source (a laboratory wall outlet or a military vehicle engine). High-powered microwaves damage equipment, especially electronics, without killing people in the area.
Two good examples are Boeing’s Advanced High-Power Microwave Missile Project (CHAMP), a high-powered microwave source mounted on a missile, and the Tactical Air Response (THOR). Force Research Laboratory to expel drone sets.
A news story about the US Air Force’s high-powered THOR weapon against microwave drones.
The origins of the Cold War
These types of energy-oriented microwave devices appeared in the late 1960s in the United States and the Soviet Union. It allowed the development of pulsed force in the 1960s. Pulsed power generates short electrical pulses with very high electrical power, i.e. high voltage (up to a few megavolts) and large electrical currents (ten kiloamp). This is a higher voltage and the number of currents in a lightning than the longest distance power transmission lines.
Plasma physicists realized at the time, for example, that if you created a 1-megabyte electron beam with a current of 10 kiloamps, the result would be 10,000 billion watts or a gigawatt of power. Converting 10% of that ray power to microwaves uses 1 gigawatt microwave using standard microwave technology from the 1940s. For comparison, the output power of today’s typical microwave ovens is about a thousand watts, a million times lower.
The development of this technology led to a subset of the US-Soviet arms race – the microwave power derby. When the Soviet Union collapsed in 1991, I and other American scientists gained access to Russian pulsed power accelerators, like the SINUS-6 still working in my lab. I had a fruitful decade collaborating with Russian colleagues, and it quickly ended after Vladimir Putin came to power.
Currently, research on high-power microwaves continues in the US and Russia, but has exploded in China. I have been visiting laboratories in Russia since 1991 and laboratories in China since 2006, and China is investing in its activities in the US and Russia. Dozens of countries now have active high-power microwave research programs.
Lots of power, little heat
Although these high-power microwave sources generate very high levels of power, they repeatedly generate short pulses. For example, my lab’s SINUS-6 generates an output pulse in the order of 10 nanoseconds or a millionth of a second. So even when the output power is generated at 1 gigawatt, the 10 nanosecond pulse has only 10 joules. Seeing this, an average microwave oven for one second generates one kilojoule or a thousand joules of energy. It usually takes about 4 minutes to boil a cup of water, which corresponds to an energy of 240 kilojoules.
Therefore, the microwaves generated by these high-power microwave weapons do not produce a significant amount of heat, much less cause people to explode like baked potatoes.
High power is important in these weapons because the creation of very high immediate power provides very high immediate electric fields, which scale as a square root of power. It is these high electric fields that can disrupt electronics, which is why the Department of Defense is interested in these devices.
How people affect you
The National Academies report links high-power microwaves to impacts on people through the Frey effect. The human head acts as a low-frequency microwave antenna receiver. Microwave pulses at these frequencies can cause people to hear sounds, which is one of the symptoms reported by affected U.S. workers. Other symptoms of Havana syndrome include headaches, nausea, hearing loss, insomnia, and cognitive problems.
The report notes that electronic devices were not interrupted in the attacks, which suggests that the power levels required for the Frey effect are lower than those that would be required for attacks on electronics. It would match a high-powered microwave weapon at a distance from the targets. Power is drastically reduced by the distance through the law of inverse squares, which means that one of these devices can cause the target power level to be too low to affect the electronics but can cause the Frey effect.
The Russians and Chinese certainly have the ability to select high-power microwave sources similar to those used in Cuba and China. The truth – and why – of what actually happened to U.S. workers in Cuba and China may remain a mystery, but the technology involved probably comes from the physics of textbooks, and the world’s military powers continue to develop and expand.
Edl Schamiloglu, Professor of Electrical and Computer Engineering, Associate Dean for Research and Innovation, wrote at the School of Engineering, University of New Mexico.
Originally published in The Conversation.