The New York Times publicizes Nikola Tesla's particle Beam research

The term teleforce refers to Nikola Tesla's macroscopic charged particle beam projector.

The device was based upon a large Van de Graaff generator of unique design and a special type of open-ended vacuum tube. It comprised a system for the acceleration of minute tungsten or mercury particles to a velocity of about 48 times the speed of sound. The projectiles were propelled out of the tube by electrostatic repulsion.

According to Tesla production of the particle beam is dependent upon four inventions of the following nature:

A method and apparatus for producing rays and other manifestations of energy in free air, eliminating the high vacuum necessary at present for the production of such rays and beams. This is accomplished with a novel form of high vacuum tube, one end of which is open to the atmosphere. The projectiles are accelerated in a vacuum and then conducted into the atmosphere through a valvular conduit.

A method and process for producing very great electrical force in the range of 60,000,000 volts to propel the particles to their objective. Tesla specified that this could be done with a large electrostatic generator on a new principle and of very great power, in many respects similar to a Van de Graaff generator. In place of a charge-carrying belt it employs a circulating stream of desiccated air that is propelled through a hermetically sealed ductwork by a Tesla disc blower. A Wardenclyffe type apparatus could also be used for this purpose.

A method for amplifying this process in the second invention. The exterior of the high potential terminal is equipped with numerous bulbs of some insulating material each containing, “an electrode of thin metal sheet suitably rounded” and “exhausted to the highest vacuum obtainable.”

A new method for producing a tremendous electrical repelling force. It appears this would be applied to the projector or gun element of the system in the form of “provisions for imparting to a minute particle an extremely high charge.” While the specific details about this aspect of the design are not readily apparent, it seems that strict attention to the fulfillment of requirements 1, 2 and 3 is critical to success. In Tesla’s words, “by the application of my discoveries it is possible to increase the force of repulsion more than a million times and what was heretofore impossible is rendered easy of accomplishment.”

The tube would project a single row of highly charged particles and there would be no dispersion, even at great distance. Because the cross section of the charge carriers could be reduced to almost microscopic dimensions and since the charged particles would self-focus via "gas focusing," an immense concentration of energy, practically irrespective of distance, could be attained. In 1940 Tesla estimated that each station would cost no more than $2,000,000 and could have been constructed in a few months.

But while it will make every nation safe against any attack by a would-be invader, Dr. Tesla added, the death-beam by its nature could not be employed similarly as a weapon for offense. For this death-beam, he explained, could be generated only from large, stationary and immovable power plants, stationed in the manner of old-time forts at various strategic distances from each country's border. They could not be moved for the purposes of attack.
An exception, however, he added, must be made in the case of battleships, which, he said, would be able to equip themselves with smaller plants for generating the death-beam, with enough power to destroy any airplane approaching for attack from the air.”

— Nikola Tesla

Nikola Tesla, one of the truly great inventors who celebrated his eighty-fourth
birthday on July, 10 tells the writer that he stands ready to divulge to the United States government the secret of his "teleforce," of which he said," airplane motors would be melted at a distance of 250 miles, so that an invisible 'Chinese Wall of Defense' would be built around the country against any enemy attack by an enemy air force, no matter how large.
This "teleforce" is based on an entirely new
principle of physics, that "no one has ever dreamed about," different from the principles embodied in the in his inventions relating to the transmission of electrical power from a distance, for which he has received a number of basic patents. This new type of force Mr. Tesla said, would operate through a beam one-hundred-millionth of a square centimeter in diameter, and could be generated from a special plant that would cost no more then $2,000,000 and would take only about three months to construct.