VASIMR

The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) system encompasses three linked magnetic cells. The "Plasma Source" cell involves the main injection of neutral gas (typically hydrogen, or other light gases) to be turned into plasma and the ionization subsystem. The "RF Booster" cell acts as an amplifier to further energize the plasma to the desired temperature using electromagnetic waves. The "Magnetic Nozzle" cell converts the energy of the plasma into directed motion and ultimately useful thrust.

Coupled with nuclear power this new type of rocket technology could dramatically shorten human transit times between planets (less than 3 months to Mars) and propel robotic cargo missions with a very large payload mass fraction. Trip times and payload mass are major limitations of conventional and nuclear thermal rockets because of their inherently low specific impulse (less than 1000 seconds). Plasma rockets such as VASIMR enable a very high specific impulse (greater than 10,000 seconds.) For these missions VASIMR will operate with hydrogen or deuterium propellant, both are abundant throughout the known universe.

The VASIMR has two additional important features that distinguish it from other plasma propulsion systems:
1. Ability to vary the exhaust characteristics (thrust and specific impulse) in order to optimally match mission requirements. This results in the lowest trip time with the highest payload for a given fuel load.
2. VASIMR is driven by electromagnetic (RF) waves and has no physical material electrodes in contact with the hot plasma. This results in greater reliability and longer life and enables a much higher power density than competing designs.

4-th State of Matter
The first step to understanding how a plasma rocket operates is learning about plasma. A plasma state can be achieved when a substance in its gaseous state is heated to very high temperatures - tens of thousands to millions of degrees. At this temperatures, electrons are stripped, or lost, from the neutral atoms.

In the overheated gas, electrons, which hold a negative charge, and ionized atoms, which hold a positive charge, mixed together making an electrically neutral "soup" of charged particles that is a plasma. This is a very common occurrence in nature. In fact, 99 percent of the visible universe is in some form of a plasma state, including lightning, very hot flames, nebulas, the Sun and other stars. The plasmas at the extreme temperatures required of a plasma rocket cannot be contained by any known material. Fortunately, plasmas can be controlled by a magnetic field.
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Superconducting Turbojet

An all-electric aircraft could soon appear over the horizon thanks to high-flying scientific research published today in the Institute of Physics' journal, Superconductor Science and Technology. The new type of aircraft, currently on the drawing board, could be far more efficient than conventional aircraft, produce less greenhouse emissions, and be quieter.

Air travel is on the increase, but it comes at a price in terms of the emissions driving climate change. Aircraft currently account for about 5% of UK emissions with a single long-haul flight the equivalent of a ton of carbon dioxide per passenger. With such worrying figures making the headlines, alternatives to combustion-based propulsion systems could be the key.

Superconducting motors could be one such alternative, according to scientists in America. Philippe Masson and Cesar Luongo from Florida State University, who have collaborated with Gerald Brown at NASA and Danielle Soban at Georgia Institute of Technology, explain that because superconductors lose no energy through electrical resistance, they could be very efficient components for a new type of aircraft propulsion.

The researchers explain that to build an electric aircraft will require propulsion motors that are high power, lightweight and compact. Current technology cannot meet these demands because an electric motor using conventional magnets can weigh up to five times as much as conventional jet engine and not be as fuel efficient.

In contrast, a superconducting motor would be very lightweight and far more efficient electrically, generating three times the torque of a conventional electric motor for the same energy input and weight. In addition, an electric aircraft would be far quieter than a conventional jet as there are no internal combustion processes involved. It is the combustion of fossil fuels to drive a conventional aircraft that makes them so noisy.

However, superconducting magnets not only have to be cold, but require a unique energy supply. Masson and his colleagues believe they could solve both problems by using chilly liquid hydrogen to run an electric fuel cell. Liquid hydrogen is cold enough to make the superconducting magnets work but also has four times as much energy weight for weight than aviation fuel.

A fuel cell produces no polluting emissions, just warm water as the hydrogen combines with oxygen. This, say the researchers would mean zero carbon emissions from the aircraft as it flies. "The idea is to reduce the emissions from the aircraft and airports," explains team leader Masson, "The energy needed to produce the liquid hydrogen could come from a remote powerplant". Such a powerplant might be solar or wind powered.

"We could potentially build a superconducting motor and generator smaller than a gas turbine, which would make possible electric propulsion," says Masson. Electrical propulsion would not only decrease emissions but also reduce to a minimum the needs for maintenance as all hydraulic systems would be eliminated, he adds. The team has designed such systems with high fidelity models and optimization tools.

Masson adds that the team is now looking for an industrial partner to build a prototype of the superconducting "turbofan". "The technology is there," he says, "it is a matter of finding a source of funding."

Original Source: Institute of Physics, News
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Where is The Proton?

Scientists Discover Footprints Of Shared Protons

This week in Science, Yale researchers present "roadmaps" showing that shared protons, a common loose link between two biological molecules, simply vibrate between the molecules as a local oscillator, rather than intimately entangling with the molecular vibrations of the attached molecules.

The paper reports clear "roadmaps" for the widely varying, characteristic vibrational frequencies that occur when an excess proton binds together simple nitrogen and oxygen containing molecules.

Rather than studying the proton-trapped pairs of molecules in crystals or in solution at room temperature, as has been common in the past, Johnson's team made their measurements of proton interactions with 18 simple molecules by isolating them in the gas-phase and cooling them to about 50 Kelvin by taking advantage of recent advances in argon nanomatrix spectroscopy.

"Historically it has been very difficult to isolate the signature of an excess proton in a complex environment like a cell membrane, and say with confidence 'Aha, I have one,'" said Johnson. "The proton is in constant motion in a warm, disordered medium, which causes its natural vibrational frequency to spread out over a huge spectral range. As a result, its 'signature' is often thought to comprise the continuous 'junk' background in the vibrational spectra of protonated samples."

"When we cool the isolated systems, the protons sing out their sharp vibrational frequencies, and therefore provide clear signatures that are characteristic of each kind of interaction," said Johnson.



Two oxygen atoms on different molecules are connected by their mutual attraction to an extra proton, shown as a fuzzy ball between them. The presence of such intermolecular binding can now be identified by monitoring the precise vibrational frequency of the bridging proton. (Credit: Image courtesy of Yale University)

The research shows that the extra proton is associated with a specific pair of atoms on the two tethered molecules, participating in partial chemical bonds to both. "In biological systems, any time you have molecules with a nitrogen or oxygen, and add in an extra proton, the proton forms a bond with one of the extra electron pairs that are available," according Johnson. "It crashes the party and changes the character of the molecule."

Extending Johnson's analogy, if another molecule containing nitrogen or oxygen comes by, the proton crashes that party, too. Because the proton is not deciding between one molecule and the other, it is creating a bond between them - crashing both parties at the same time. "A proton is a great handshaker that works the room until it gets to where it is needed," he said.

This motif is the generic intermediate involved in passing a proton through a biological membrane. Each paired interaction forms a locally stable intermediate. In a sense, the oxygen atoms in water molecules chaperone protons between oxygen and nitrogen atoms on organic structures. For example, the primary events in trans-membrane proton pumps require passing protons through many relay steps across the cell membrane.

In earlier studies, Johnson looked only at water molecules trapping protons. This study expands the work to biologically relevant molecules that contain oxygen and nitrogen atoms. In it the researchers were able to look at how stiff the proton trap is between two molecules, and how this stiffness depends on the properties of the molecules to which the protons are attached.

"The strength with which the proton is grabbed by a nitrogen - or oxygen- containing molecule is highly affected by the environment," said Johnson. "So, we systematically changed that environment over a huge range and followed how the localization of the proton changed. We found that the way the proton is localized depends very much on the chemical properties of the atoms you are trapping it with."
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Mew NMR Methods by Kurt W Zilm
LUMO Analogy among three fluorides
Argon Nanomatrix Spectroscopy by Mark A Johnson
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