A Japanese death ray?

If anyone came close to creating a death ray weapon by the end of the Second World War, it was the Japanese army. It wouldn't have helped them much, however, as they weren't at war with rabbits. According to Richard Overy in The Air War 1939-1945 (Washington: Potomac Books, 2005 [1980]), 195:

The lack of satisfactory evaluative machinery led for example to the diversion of considerable resources to the search for a 'death ray'; a search that Western powers had abandoned in the 1930s. By the end of the war the Japanese 'ray' could kill a rabbit after five minutes at a distance of 1,000 yards.

The reference Overy gives for this is the U.S. Strategic Bombing Survey, report 15, appendix XX, but this appears to be in error as that's online and has only ten appendices. According to this site, report 63 (Japanese Air Weapons and Tactics) does in fact discuss the death ray. Unfortunately I can't find that one (not for free, any way).

But there are a few more snippets to be found online. This is from Radar Origins Worldwide: History of Its Evolution in 13 Nations Through World War II (Trafford Publishing, 2009) by Raymond C. Watson Jr, 334-5:

The Ku-go (Death Ray) was another matter. An Article on a death-ray device invented by Nikola Tesla had been in The New York Times (July 11, 1934), and was picked up by the Japanese press. In this, Tesla was quoted as saying that his beam would "drop an army in its tracks and bring down squadrons of airplanes 250 miles away." Magnetron research at the NTRI and JRC appeared to indicate that a beam device with tremendous output power might be possible.

In 1943, work began at the Shimada City research facility on developing a high-power magnetron that, if not as capable as Tesla had boasted, could at least incapacitate an aircraft. A number of Japan's leading physicists were involved in this activity, including Sin-Itiro Tomonaga, another future Nobel laureate. By the end of the war, their effort had produced a 20-cm magnetron with a continuous output of 100 kW, far short of the desired 500 kW, which itself would likely have been insufficient for the mission. Like other Project Z efforts, documentation was totally destroyed before Japan surrendered.

It looks like there is much more in Walter E. Grunden's Secret Weapons and World War II: Japan in the Shadow of Big Science (Lawrence: University of Kansas Press, 2005), but I can only see a few of the relevant pages online. (There's also a lengthy review at Stone & Stone Second World War Books.) According to Grunden, the Japanese army (by way of the Army Institute of Scientific Research) first looked into death rays in 1930, again inspired by a newspaper article -- this time claiming that Germany had invented an 'electric wave' weapon in the First World War. The main application envisaged was air defence, but it could also be useful for coastal defence. It was concluded then that the necessary energy output was impossible with available technology, but later in the decade improvements in magnetrons made a death ray seem more feasible. As far as the actual experimental research is concerned, Grunden says the following (110-1):

Research toward developing a weapon utilizing microwaves began [at the Noborito laboratory of the AISR] around 1939 on a small scale with a team of thirty technicians. Their objectives were to determine how best to generate microwaves and how to stop an internal combustion engine by the resonance effect, and they sought to conduct basic research on the physiological effects of microwaves on live animals.

That's about all I can find (well, all that has any supporting references at all). Obviously Ku-go never was never a practical weapon, but it sounds like the Japanese army got closer to it than Grindell Matthews did, or Tesla for that matter.

Overy places Japan's death ray research in the context of wasteful research projects, arguing that both the Axis powers made poor choices as to research projects (V-2 rockets being another one). That's a bit too strong a conclusion; in research some alleyways will turn out to be blind, and anyway the Allies made some poor choices too (Lindemann's parachute mines, for example). And there was no guarantee that the Manhattan Project would result in a working atom bomb, in which case it would have been the most expensive white elephant ever. But the point is, as Overy also notes, that the Allies had the scientific resources to spare on possible dead ends, whereas Japan and (to a lesser extent) Germany did not. It's another part of the reason why the Allies won.

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21 thoughts on “A Japanese death ray?

  1. Christopher Amano-Langtree

    A death ray - interesting and given Japan's lack of scientific expertise at the time a real waste of resources. The allies had the resources to research many different strands of technology. Thus there were some failures but the important technology got developed. There was too much willpower involved in the axis research programme and not enough practicability.

  2. Erik Lund

    Hey, at least the Japanese were playing with magnetrons. When Tizard brought his to the United States, it was, "hey, why didn't we think of that?"
    (Although recession/depression driven lack of research funding will have that effect.)
    By the way, if anyone is interested in magnetrons in WWII, the research line I've worked up but never pursued focusses on their lack of tunability. The geometry of the magnetron determines its frequency, and so you have to machine them to get the frequency you want, which is rather tough for centimetric radiation. The British 10cm magnetrons all broadcast around 9.8 cm, but each magnetron had to be individually matched to its receiver. There's some great articles in the special issues of _Journal of the Institution of Electrical Engineers_ that came out in 1948 and 1949.

  3. Raymond C. Watson, Jr.; Ph.D., P.E.

    Subsequent to finishing the book (Radar Origins Worldwide) previously referenced, I found a number of additional sources concerning the Japanese death-ray work. In a brief report from Captain C. G. Grimes of the U.S. Naval Technical Mission to Japan, dated 17 January 1946. there is an Enclosure entitled "Magnetrons and Other Vacuum Tubes Used by the Ninth Military Technical Laboratory in Death Ray Experiments." Item E of the Enclosure includes the following:

    "A large multple segment magnetron, designed to deliver 100 kw CW output at approximately 400 mc, was in the process of development when the war ended. . . . It was intended to connect ten of these magnetrons in parallel to obtain 1000 kw (CW) output but details had not been worked out."

    This may be found on the Web at the following URL:


    The reference to "rabbits" likely comes from an interview (#212) by the IEEE Center for the History of Electrical Engineering with Dr. Shigeru Nakajima, who was the brother of Captain (Dr.) Yoji Ito (see p. 315 of my book) who coordinated the project. Read it for yourself at:


  4. Post author

    Thanks very much for this, Raymond, most interesting. Especially Nakajima's suggestion that Japan invented cavity magnetrons a year before Britain did, ie. in 1939. Probably lucky for the Allies that they used them for death ray research instead of spending the time developing AI radar or ASW radar!

    I came across a couple of references on the web to testimony on the death ray by physicist Karl Taylor Compton (then head of MIT) given to the (presumably U.S.) Senate Committee on Military Affairs on 25 October 1945, e.g. here. Perhaps you know of it? I couldn't find any reference in the New York Times so it may have been a closed hearing.

  5. Raymond C. Watson, Jr.; Ph.D., P.E.

    Immediately after Japan's surrender, Dr. Compton headed the United States Scientific Intelligence Commission to quickly examine the high-technology developmemts in Japan during the war. I have never seen a full copy of the Commission's findings (commonly called the Compton Report, but I am certain that it was initially classified. There are references, however, in a number of subsequent papers, mainly those of electronics, radio, and radio -- particulrly related to magnetrons.

  6. Raymond C. Watson, Jr.; Ph.D., P.E.

    A copy of Karl Compton's draft report "Mission to Tokyo" of findings during the scientific intelligence survey for the U.S. military in Japan in 1945 is included in the collection archived at the Massachusetts Institute of Technology, under: Office of the President, Records of Karl Taylor Compton and James Rhyne Killian, AC 4, box X. Massachusetts Institute of Technology, Institute Archives and Special Collections, Cambridge, Massachusetts.

  7. Just some additions on sources that I did not see mentioned. The New York Times had a brief article entitled "Japanese Had 'Death Ray' in Stage of Development," 7 October 1945, p. 32. This was based on a report released by General MacArthur's headquarters.

    However, there was mention as early as 1937 about the Japanese experimenting on rabbits with a type of death ray. This can be found in Kurt Doberer's Der Elektrokrieg. I have seen only the English translation (On the Way to Electro War) which did not come out until 1942. The reference can be found on page 46 of the English version.

    As you may know, Doberer and Max Seydewitz co-authored a fairly comprehensive study entitled Todesstrahlen und Andere Kriegswaffen (Death rays and other war weapons) published in 1936.

    That's all I have on the Japanese death ray.

  8. On second thought, I have another comment. This is in reference to the Overy quotation above about the Western powers having abandoned by the 1930s the quest to develop a death ray. There were at least two instances during WW II in which the Germans tried to do so. The most ambitious was the "Sonnengewehr," or sun gun. Shortly after the German surrender, American forces came across a secret installation at Hillersleben and captured a team of German scientists working on a weapon of true science fiction dimensions. They were going to build a large space platform mounted with a more sophisticated version of Archimedes' fabled weapon and direct the concentrated heat rays of the sun to targets on earth. The scientists admitted to interrogators that it would take at least 50 years to develop and would therefore have not been of any use to the German war effort. Nevertheless, it was funded and they applied themselves to the work. A fairly detailed account appeared in the New York Times on 29 June 1945, pp. 1, 5. The title of the article is "Nazis' Scientists Planned Sun 'Gun' 5,100 Miles Up." Time magazine also featured it as "Sun Gun," 9 July 1945, p. 58. The American officer in charge of the interrogation was Lieutenant Colonel John A. Keck, an engineer in civilian life.

    The other instance was described by Mario Beck in the Leipziger Volkszeitung under the title "Schiebolds braune Sciencefiction." 16/17 April 2005.
    http://www.waloschek.de/pedro/lvz-rezension-beck-A4.pdf. This is also from Pedro Waloschek's Todesstrahlen als Lebensretter. (Norderstedt: Books on Demand, GmbH, 2004). A man by the name of Ernst Schiebold showed up one day in April 1943 at the office of Field Marshal Erhard Milch and presented a plan to construct a weapon based on powerful X-rays and protect German cities from Allied air raids. Milch agreed to fund the program, but it was canceled after about a year. There is a brief reference to this in Albert Speer's Inside the Third Reich. He related that Robert Ley came to him one day all excited and told him that death rays had been invented. Speer, who obviously did not share Ley's faith in such a wonder weapon, jokingly remarked that Ley could assume an additional title as "Commissioner for Death Rays."

  9. Post author

    Thanks for that, Bill, nice to see you here again. A decent summary of the Sun Gun can be found here; it has links to the Time and New York Times articles at the bottom. I've also found an article in Flight from 1951, but it doesn't seem to have any more information than in is the NYT article. It seems odd to be relying on press clippings after all this time. There must be something in a US government archive somewhere (or perhaps in a Raiders of the Lost Ark-style warehouse).

  10. Where else?

    There's work to be done (or is one, perhaps) on 'things that don't exist but everyone knows should (or will) exist'; ray guns, intergalactic credits, faster than light power etc. Not to mention miracle cures, the winning ticket and all the other things used to separate fools and money.

  11. Simon Gunson

    From 1937 after his studies of plasma physics in Germany, Dr. Asada Tsunesaburo advocated to the IJN Technical research lab and in particular to Admiral Yammamoto that Japan develop atomic weapons. Asada became the leading advocate of death rays, but the two are linked since Asada learned from Pro Max steenbeck the concept of developing advanced betatrons which are what death rays are based upon. During 1941 Dr Ronald richter worked for the SS at Prague university on a similar system. The germans learned that by application of a parabolic Beryllium mirror the particle beam from an advanced Tokamak type accelerator could be steered and directed against aircraft. Nazis and japanese shared their technology. During 1941 Lt cmdr Ito Yoshi studied these devices with Steenbeck, and in 1944 Capt Mitsui matao visited germany to acquire this technology for use in developing Japan's nuclear bomb by transmutation of Thorium into Uranium

  12. Post author

    I'm not sure what your point is, but this all sounds just a little dubious to me. Tokamaks weren't invented until well after the war, in the mid-1950s: they're used in nuclear fusion research, and nobody was doing that during the war. And is this the same Ronald Richter who turned up in Peron's Argentina after the war pushing bogus ideas about fusion-powering the economy?

  13. Simon Gunson

    The point is there is a whole history of world war two which for whatever reason is still concealed to the present day and these so called death ray devices did exist. Both in Germany and Japan. I reject your claim. Soviet Tokamacks were based on the know how of captured nazi scientist Prof Max Steenbeck. Rajewsky led the Nazi death ray research. An advanced synchrotron particle accelerator was captured by ALSOS at Bissingen about 27 April 1945. This was part of Forschungsstelle D under Dr Walter Dallenbach. His project was part of the nazi A-bomb project and the Rajewsky death ray project was a spin off from that. The Japanese traded information with Steenbeck who worked in the Ardenne institute.
    Lt Cmdr Ito Yoji in particular visited Japan for ten months from December 1940, to study development of artificial neutron sources and radar. That is the point

  14. Post author

    Well, 'for whatever reason' might be because it is pseudohistory allied with pseudoscience. You make a lot of claims at variance with the current consensus but present no evidence, except bits and pieces gathered from dubious sources. A bit of googling reveals this to be your standard modus operandi. I'm not interested in inflated claims about the wonders of Nazi science. Sorry.

    Lt Cmdr Ito Yoji in particular visited Japan for ten months from December 1940, to study development of artificial neutron sources and radar. That is the point

    What have neutrons got to do with radar?

  15. Kris l a

    Hitler was supposedly the one wanting to make a ray gun, or death ray to try and destroy anyone and anything that stood in his way. Mostly to use on enemy vehicles and to use at a long distance to ensure his victory. His scientists never developed it and was a failure, so they it was never thought of. Someone will try and make it, I mean if we have all this technology these days then we will

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