Newswise ALBUQUERQUE (NM) — People have resisted the temptation to test energetic materials since before the first person ever touched an uninsulated electric wire. High voltages can cause metal meters to melt.
Using a crystal less than a dime, and a laser less than a shoebox to measure millions of volts, the Sandia National Laboratories team was able to safely measure mV without actually contacting the electrical flow. (Residential voltage generally 120 Volts. )
“No one has ever measured such large voltages anywhere else in the world prior to our experiment,” stated Sandia scientist Israel Owens about his unique electrical and optical work. It was recently published in Nature’s Scientific Reports .. “For measuring high voltages, the technique is safe, efficient and inexpensive.”
“When you have a high voltage over short distances, sensors break down,” said Sandia manager Bryan Oliver. “Israel’s diagnostic can survive these high electric fields and thus enable us to determine the voltage in an environment where that was previously not possible.”
The achievement, which multiplies every electrical field reading by the same constant to determine the voltage, opens a door to several possible applications.
The work was done at Sandia’s High-Energy Radiation Megavolt Electron Source (HERMES III), where the building-sized accelerator transforms powerful pulses in electricity into photons called gamma rays. Owens stated that being able to measure Hermes III’s output voltage instead of just calculating it makes it possible to accurately determine the energies of the Gamma Rays. “And our crystal-laser system does it without disturbing the experiment environment.”
Benefits of precisely measuring the energy of gamma rays
The HERMES accelerator generates a high-energy electron beam that is stopped in very dense material and converted into a stream of gamma rays — the most energetic part of the electromagnetic spectrum. These rays can be used for sterilization, food pasteurization and medical imaging. They can also be used to measure the thickness of extremely thin materials.
Because nukes also produce gamma radiation, it is possible to create them in a laboratory to determine if civilian and military equipment can continue to function under those energy streams.
To achieve the desired output of Gamma Rays, it is necessary to calibrate the voltages used. Therefore, a sensor capable of measuring the high voltages and not causing damage is essential.
Owens said that the idea of lasers being used as remote measurement tools is not a new one. To safely measure forehead temperatures, laser infrared sensors can be used from a distance. The laser range finder can measure the room’s size without the need for the owner to pace the distance.
” Our procedure is slightly different. We aren’t pointing the laser at an object to measure its potential voltage.” he explained. “We determine that information by using our laser simply to interrogate a secondary object — a lithium niobate crystal.”
Tiny crystals altered by huge energy fields
The crystal, less than a half-inch long, is placed so that the electrical field passes through it broadside, at right angles to the polarized laser beam travelling along the crystal’s axis.
The electric field alters the crystal’s ability to transmit light. It causes its photons’ speeds to vary in the polarized beam’s horizontal and vertical directions. The polarized light is then able to rotate, changing how much enters the photodetector. This converts the intensity of the laser beam into a simple voltage that can be read with an oscilloscope.
” The voltage measured by the oscilloscope directly correlates with the strength of the electrical field from which the voltage can calculated,” Owens said. “In our experiments, tens to megavolts were converted into hundreds of microvolts on an oscilloscope. A megavolt is one million volts. A millivolt, on the other hand, is one thousandth of a trillionth of a degree. )
” The signal is already in the right form. We just need to multiply it by a fixed constant. There is also no need to perform any tedious calibrations or complicated post processing to determine the electric fields and voltages.”
The high voltages measured with the new sensor closely matched what was expected through calculations and other indirect measurements, said Owens.
The new technique might not only have the advantage of accurately measuring the gamma radiation energy, Owens stated.
” At the moment this device is only used for research purposes. However, as it develops, it may be used in accelerator facilities to provide voltage readings at remote locations.
The technique could also be used, Owens stated, by the power transmission industry and lightning research centers, as well as other areas that require remote monitoring or measurement of high-energy sources. It could also detect an electrical short in a wall at a distance by disrupting the electromagnetic field around the current-carrying cable. This would enable non-invasive detection and diagnosis of faults in the circuitry. This research was supported by the National Nuclear Security Administration.
Sandia National Laboratories is a multimission laboratory operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration. Sandia Labs is responsible for major research and development in nuclear deterrence and global security. Its main facilities are located in Albuquerque (New Mexico) and Livermore (California).