THOR Hammers Drone Swarm with High-Power Microwaves

An experimental directed energy weapon developed by the Air Force Research Laboratory successfully disabled a swarm of drones last month—its first test on such a scale. 

The Tactical High-power Operational Responder, or THOR, has been in development for years now, generating high levels of interest within the military and beyond. THOR uses bursts of high-power microwave energy to disable small unmanned systems, causing them to drop from the sky. 

An April 5 demonstration at Kirtland Air Force Base, N.M., pitted “numerous” drones of a sort THOR had not faced before against the weapon in the “first test of this scale in AFRL history,” according to a release.

“THOR was exceptionally effective at disabling the swarm with its wide beam, high peak powers, and fast-moving gimbal to track and disable the targets,” said Adrian Lucero, THOR program manager, in the release.  

Ken Miller, AFRL’s high power electromagnetics division chief, declared the demonstration a “success.” 

An AFRL spokesperson declined to say how many or what kinds of drones were used or whether calling the test a success could be taken to mean THOR successfully downed every drone in the swarm. Regardless, however, defeating a drone swarm significantly exceeded the 2019 demonstration at Kirtland of the system knocking down a single drone.  

The 2019 test was followed in 2020 by an announced overseas demonstration alongside other directed energy weapons, but results of that demonstration were never disclosed. In 2021, the lab announced the U.S. Army was investing in the system.  

Also in 2021, AFRL announced it was developing a follow-on system to THOR called “Mjolnir,” the name of the hammer wielded by the Norse god Thor. In 2022, the lab selected Leidos to build Mjolnir, saying the new weapon would use the same technology as THOR “but will add important advances in capability, reliability, and manufacturing readiness.”  

Directed energy weapons have long been seen as promising, but as drones have become cheaper and more capable, military leaders have become increasingly worried about the threat posed by swarms of autonomous drones in a coordinated attack.  THOR was developed with that theat in mind.  

Using a wide beam, THOR can take out multiple drones at a time, using a video game-like interface. The weapon can be carried in a C-130 and quickly assembled on the ground. It can leverage other detection and targeting systems or use its own. 

“[THOR] is an early demonstrator, and we are confident we can take this same technology and make it more effective to protect our personnel around the world,” Capt. Tylar Hanson, THOR deputy program manager, said in a statement.