Anyone who has flown on a commercial aircraft since 9/11 knows that the new security mechanisms that intend to keep us safe can be annoying as well. Few will argue that having to take off half your clothes just to get on an airplane might be considered excessive and time-consuming.
Earlier this month U.S. authorities participating in a TSA audit were able to smuggle components through checkpoints at major airports in the United States, even with alerted security measures.
Scientists at the U.S. Department of Energy’s Argonne National Laboratory have developed a new source of so-called T-rays that could lead to a totally new method of detecting weapons in airports as well as new medical diagnostic devices that don’t harm cells and work better than current devices.
T-rays, or terahertz rays, function similarly to x-rays or any other electromagnetic radiation. However, whereas x-rays radiate at frequencies above the visible light spectrum, t-rays operate just below it. High-frequency t-rays is actually low-frequency infra-red radiation.
T-ray devices can penetrate leather, fabric, cardboard and paper but can’t penetrate metals or water. T-rays can also penetrate the human body by about half a centimeter making it appropriate for diagnosing medical problems. Most technology in airports today use some form of x-ray technology instead, which can be harmful to passengers if used incorrectly.
The lead scientist on the project, Ulrich Welp of the Argonne Materials Science Division and his team of international researchers have been able to produce t-rays using superconducting crystals grown at the University of Tsukuba in Japan.
The crystals are arranged into what’s called Josephson junctions, which exhibit special properties when electrical voltage is applied. Voltage applied to the crystals causes an alternating current to flow back and forth across the junctions at a frequency proportional to the voltage. Researchers found that tiny voltages of around two millivolts per junction could produce frequencies in the terahertz range.
The trick to producing t-rays is to get the around 1,000 stacked Josephson junctions to oscillate at the same frequency. Welp said, “That's been the challenge all along. If one junction oscillates up while another junction oscillates down, they'll cancel each other out and you won't get anything.”
The researchers were able to achieve the same oscillation frequency of the junctions by shaping the superconducting crystals into resonant cavities. Currently the researchers are able to generate t-rays in the 0.4 to 0.85 terahertz range with a signal power of up to 0.5 microwatts.
Welp says, “The more power you have, the easier it is to adopt this technology for all sorts of applications. Our data indicate that the power stored in the resonant cavities is significantly larger than the detected values, though we need to improve the extraction efficiency. If we can get the signal strength up to 1 milliwatt, it will be a great success."