The AIP is made up of various member societies. Its corporate headquarters are at the American Center for Physics in College Park, Maryland, but the institute also has an office in Melville, New York and Beijing, China.
The focus of the AIP appears to be organized around a set of core activities. The first delineated activity is to support member societies regarding essential society functions. This is accomplished by annually convening the various society officers to discuss common areas of concern. A range of topics is discussed which includes scientific publishing, public policy issues, membership-base issues, philanthropic giving, science education, science careers for a diverse population, and a forum for sharing ideas.
Another core activity is publishing the science of physics in research journals, magazines, and conference proceedings. Other core activities are tracking employment and education trends with six decades of coverage, being a liaison between research science and industry, historical collections and outreach programs, and supporting science education initiatives and supporting undergraduate physics. One other core activity is as an advocate for science policy to the U.S. Congress and the general public.
American Institute of Physics research articles from Innovation Toronto
- Co-Crystals Successfully Turn Liquids into Solids – August 13, 2014
- New way to combat bacterial biofilm formation with titanium encrusted with gold nanoparticles – July 6, 2014
- Magnetic cooling enables efficient, ‘green’ refrigeration – June 11, 2014
- Future Computers that are “Normally Off” | Spintronics
- Indian American achieves breakthrough in computing technology
- Interdisciplinary Research Partnerships Set Out to Uncover the Physics of Cancer
- New Thermoelectronic Generator
- Brighter & Clearer Ultrasound Images + Improved Diagnosis
- Seeing in the Dark
- Measuring Blood Sugar With Light
- Low-Priced Plastic Photovoltaics
- Futuristic Copper Foam Batteries Get More Bang for the Buck
- Wrangling Flow to Quiet Cars and Aircraft
- Solar Power’s Future Brawl
- Bright, Laser-Based Lighting Devices
- Fusion, Anyone?
- Densest Array of Carbon Nanotubes Grown to Date
- Promising New Alloy for Resistive Switching Memory
- The “50-50″ Chip: Memory Device of the Future?
- Indiana Jones Meets George Jetson
- Catching Cancer Early by Chasing It
- New Low-Cost, Transparent Electrodes
- Electric Rocket Engines: Magnetic Shielding of Ion Beam Thruster Walls
- Mining for Heat
- Bioreactor Redesign Dramatically Improves Yield
- Miniature Sandia sensors to Help Climate Research
- New ‘Soft’ Motor Made from Artificial Muscles
- Nano-Coating Doubles Rate of Heat Transfer
- Bold New Approach to Wind ‘Farm’ Design May Provide Efficiency Gains
- Replacing Batteries May Become a Thing of the Past, Thanks to ‘Soft Generators’
- A New Way to Double Storage Capacity for Magnetic Media
- Invisibility Cloaks and More
- Trapped Sunlight Cleans Water
- Self-Healing Autonomous Material Comes to Life
- Generating Energy from Ocean Waters Off Hawaii
- Stability and Utility of Floating Wind Turbines Shown in New Study
- India and China Wise Up to Innovation
- How Supercomputers Will Yield a Golden Age of Materials Science
- “Flipping the switch” reveals new compounds with antibiotic potential
- NYU-Poly Nano Scientists Reach the Holy Grail in Label-Free Cancer Marker Detection: Single Molecules
- Quantum Teleportation in Space Explored as Message Encryption Solution
- There Should Be Grandeur: Basic Science in the Shadow of the Sequester
- South Korea Makes Billion-Dollar Bet on Fusion Power
- Computer Memory Could Increase Fivefold From UT Research
- BGU Develops Powerful New Solar Cell
- New Tractor Beam Proposal Relies on Negative Radiation Pressure
- Unconventional geothermal techniques a potential game changer for U.S. energy policy
- Ohm Run: One-Atom-Tall Wires Could Extend Life of Moore’s Law
- Quantum Dots and More Used to Beat Efficiency Limit of Solar Cells
- 1 Percent versus the 99 Percent–A Case for Open Access
- Precision-Controlled Microbots Show They Could Take On Industrial-Scale Jobs
- Portable Hydrogen Reactor for Fuel Cells
- Twisted Radio Waves Could Expand Mobile-Phone Bandwidth by a Factor of 9
- This is the “go to” guy: The alternative choice
- Is Spent Nuclear Fuel a Waste or a Resource?
- Steel City Project Converts Gasoline Cars to Run on Electricity
- U.S. Seeks to Make Science Free for All
New method can deposit nanomaterials onto flexible surfaces and 3-D objects
Printing has come a long way since the days of Johannes Gutenberg. Now, researchers have developed a new method that uses plasma to print nanomaterials onto a 3-D object or flexible surface, such as paper or cloth. The technique could make it easier and cheaper to build devices like wearable chemical and biological sensors, flexible memory devices and batteries, and integrated circuits.
One of the most common methods to deposit nanomaterials–such as a layer of nanoparticles or nanotubes–onto a surface is with an inkjet printer similar to an ordinary printer found in an office. Although they use well-established technology and are relatively cheap, inkjet printers have limitations. They can’t print on textiles or other flexible materials, let alone 3-D objects. They also must print liquid ink, and not all materials are easily made into a liquid.
Some nanomaterials can be printed using aerosol printing techniques. But the material must be heated several hundreds of degrees to consolidate into a thin and smooth film. The extra step is impossible for printing on cloth or other materials that can burn, and means higher cost for the materials that can take the heat.
The plasma method skips this heating step and works at temperatures not much warmer than 40 degrees Celsius. “You can use it to deposit things on paper, plastic, cotton, or any kind of textile,” said Meyya Meyyappan of NASA Ames Research Center. “It’s ideal for soft substrates.” It also doesn’t require the printing material to be liquid.
The researchers, from NASA Ames and SLAC National Accelerator Laboratory, describe their work in Applied Physics Letters, from AIP Publishing>.
They demonstrated their technique by printing a layer of carbon nanotubes on paper. They mixed the nanotubes into a plasma of helium ions, which they then blasted through a nozzle and onto paper. The plasma focuses the nanoparticles onto the paper surface, forming a consolidated layer without any need for additional heating.
The team printed two simple chemical and biological sensors. The presence of certain molecules can change the electrical resistance of the carbon nanotubes. By measuring this change, the device can identify and determine the concentration of the molecule. The researchers made a chemical sensor that detects ammonia gas and a biological sensor that detects dopamine, a molecule linked to disorders like Parkinson’s disease and epilepsy.
But these were just simple proofs-of-principle, Meyyappan said. “There’s a wide range of biosensing applications.” For example, you can make sensors that monitor health biomarkers like cholesterol, or food-borne pathogens like E. coli and Salmonella.
Because the method uses a simple nozzle, it’s versatile and can be easily scaled up. For example, a system could have many nozzles like a showerhead, allowing it to print on large areas. Or, the nozzle could act like a hose, free to spray nanomaterials on the surfaces of 3-D objects.
“It can do things inkjet printing cannot do,” Meyyappan said. “But anything inkjet printing can do, it can be pretty competitive.”
The method is ready for commercialization, Meyyappan said, and should be relatively inexpensive and straightforward to develop. Right now, the researchers are designing the technique to print other kinds of materials such as copper. They can then print materials used for batteries onto thin sheets of metal such as aluminum. The sheet can then be rolled into tiny batteries for cellphones or other devices.
Learn more: Printing nanomaterials with plasma
Hall thrusters are advanced electric rocket engines primarily used for station-keeping and attitude control of geosynchronous communication satellites and space probes.
Recently, the launch of two satellites based on an all-electric bus has marked the debut of a new era – one in which Hall thrusters could be used not just to adjust orbits, but to power the voyage as well. Consuming 100 million times less propellant or fuels than conventional chemical rockets, a Hall thruster is an attractive candidate for exploring Mars, asteroids and the edge of the solar system. By saving fuel the thruster could leave room for spacecraft and send a large amount of cargo in support of space missions. However, the current lifespan of Hall thrusters, which is around 10,000 operation hours, is too short for most space explorations, which require at least 50,000 operation hours.
To prolong the lifespan of Hall thrusters, a team of researchers from the French National Center for Scientific Research have experimentally optimized the operation of a novel, wall-less thruster prototype developed a year ago by the same team. The preliminary performance results were satisfactory, the team said, and pave the way toward developing a high-efficiency wall-less Hall thruster suitable for long-duration, deep space missions. The researchers present their work in a paper published this week in the journal Applied Physics Letters, from AIP Publishing.
Hall thrusters are electric rocket engines using a super high speed (on the order of 45,000 mph) stream of plasma to push spacecraft forward. Their operating principle relies on the creation of a low-pressure quasi-neutral plasma discharge in a crossed magnetic and electric field configuration. The propellant gas, typically xenon, is ionized by electrons trapped in the magnetic field.
In the conventional Hall thruster configuration, the magnetized discharge is confined to an annular dielectric cavity with the anode at one end, where the gas is injected, and an external cathode injecting electrons. Ionization of the propellant gas occurs inside the cavity, with ions accelerated by the electric field that stretches from the interior to the exterior of the cavity.
“The major drawback of Hall thrusters is that the discharge channel wall materials largely determine the discharge properties, and consequently, the performance level and the operational time,” said Julien Vaudolon, the primary researcher in the Electric Propulsion team led by Professor Stéphane Mazouffre in the ICARE-CNRS Laboratory, France.
Vaudolon explained that the wall materials play a role in the plasma properties mainly through secondary electron emission, a phenomenon where high-energy ions hit the channel wall surface and induce the emission of secondary electrons. Additionally, the erosion of the discharge cavity walls due to bombardment of high-energy ions shortens the thruster’s lifetime.
“Thus, an effective approach to avoid the interaction between the plasma and the discharge channel wall is to move the ionization and acceleration regions outside the cavity, which is an unconventional design named a Wall-Less Hall Thruster,” Vaudolon said.
Last year, the team developed a small-scale, wall-less thruster prototype based on a classical Hall thruster. At first the researchers simply moved the anode to the channel exhaust plane. However, this first wall-less thruster turned out to be a low-performance device, as the magnetic field lines are perpendicular to the thruster axis, which cross the anode placed at the channel exhaust plane.
“Magnetic fields are used to trap hot electrons injected from the external cathode and prevent them from reaching the anode,” Vaudolon said. “Basically an electron travels along the magnetic field line. If the magnetic field lines cross the anode, a large portion of hot electrons will be collected at the anode and won’t take part in the ionization of the xenon atoms, resulting in high discharge current, low ionization degree, and consequently, low performance level.”
To optimize the wall-less prototype and make the magnetic lines avoid the anode surface, the team rotated the magnetic barrier by 90 degrees, so that it injected the magnetic field lines parallel with the axial direction. The anode was still placed at the channel exhaust plane, but its shape is curved to avoid any interaction with the magnetic field lines.
Based on the PPS-Flex, a 1.5 kilowatts class thruster designed by the GREM3 Team at LAPLACE Laboratory, France and capable of modifying the magnetic field topology over a broad range of configurations, the team has validated their optimization strategies by modifying several parts and parameters of the thruster. The measurement of some operation parameters such as the thrust level, anode efficiency and far-field ion properties displayed a satisfactory performance level. However, Vaudolon said, some further optimization is still needed for the thruster’s efficient operation at high power.
“The wall-less thruster allows scientists to observe regions of the plasma previously hidden behind the channel walls. Now the plasma region can be observed and diagnosed using probes and/or laser diagnostic tools,” Vaudolon said. He also pointed out that the access to key regions of the plasma facilitates a thorough investigation of plasma instability and small-scale turbulence for a better understanding of the discharge physics and anomalous electron transport.
“Despite decades of research, the physics of Hall thrusters is still far from being understood, and the device characterization methods still rely on trials and testing, leading to expensive efforts,” Vaudolon said. “The major difficulty in developing predictive simulations lies in modeling the interaction between plasma and wall. The wall-less design would be an effective solution, potentially making future predictive simulations feasible and reliable.”
Tunable radiation source that reaches coveted THz region of spectrum could be used for medical imaging or security applications
Terahertz radiation, the no-man’s land of the electromagnetic spectrum, has long stymied researchers. Optical technologies can finagle light in the shorter-wavelength visible and infrared range, while electromagnetic techniques can manipulate longer-wavelength radiation like microwaves and radio waves. Terahertz radiation, on the other hand, lies in the gap between microwaves and infrared, whether neither traditional way to manipulate waves works effectively. As a result, creating coherent artificial sources of terahertz radiation in order to harness it for human use requires some ingenuity.
Difficulties of generating it aside, terahertz radiation has a wide variety of potential applications, particularly in medical and security fields. Because it’s a non-ionizing form of radiation, it is generally considered safe to use on the human body. For instance, it can distinguish between tissues of different water content or density, making it a potentially valuable tool for identifying tumors. It could also be used to detect explosives or hidden weapons, or to wirelessly transmit data.
In a step towards more widespread use of terahertz radiation, researchers have designed a new device that can convert a DC electric field into a tunable source of terahertz radiation. Their results are published this week in the Journal of Applied Physics, from AIP Publishing.
This device exploits the instabilities in the oscillation of conducting electrons at the device’s surface, a phenomenon known as surface plasmon resonance. To address the terahertz gap, the team created a hybrid semiconductor: a layer of thick conducting material paired with two thin, two-dimensional crystalline layers made from graphene, silicene (a graphene-like material made from silicon instead of carbon), or a two-dimensional electron gas. When a direct current is passed through the hybrid semiconductor, it creates a plasmon instability at a particular wavenumber. This instability induces the emission of terahertz radiation, which can be harnessed with the help of a surface grating that splits the radiation.
By adjusting various parameters — such as the density of conduction electrons in the material or the strength of the DC electric field — it is possible to tune the cutoff wavenumber and, consequently, the frequency of the resulting terahertz radiation.
“[Our work] demonstrates a new approach for efficient energy conversation from a dc electric field to coherent, high-power and electrically tunable terahertz emission by using hybrid semiconductors,” said Andrii Iurov, a researcher with a dual appointment at the University of New Mexico‘s Center for High Technology Materials and the City University of New York. “Additionally, our proposed approach based on hybrid semiconductors can be generalized to include other novel two-dimensional materials, such as hexagonal boron nitride, molybdenum disulfide and tungsten diselenide.”
Other labs have created artificial sources of terahertz radiation, but this design could enable better imaging capabilities than other sources can provide. “Our proposed devices can retain the terahertz frequency like other terahertz sources but with a much shorter wavelength for an improved spatial resolution in imaging application as well as a very wide frequency tuning range from a microwave to a terahertz wave,” said Iurov.