The largest tokamak fusion device is ITER, located in Europe. The timetable for ITER has dramatically slipped with 2040 now the estimated date for proof of concept. Will it become the model for nuclear energy in the near future. If so it will join solar, wind, geothermal and tidal energy as zero-emission technologies that can replace fossil fuels.
But Ebrahimi sees something else coming out of the NSTX-U. She sees the utility of the technology for rocket propulsion. Instead of enhanced magnets containing the plasma produced within a tokamak, the energy could be directed out the back of a rocket.
Ebrahimi, in an interview in January of this year, described how she arrived at the concept. “I had the idea in 2017…thinking about the similarities between a car’s exhaust and the high-velocity exhaust particles created by PPPL’s National Spherical Torus Experiment. During its operation, this tokamak produces magnetic bubbles called plasmoids that move at around 20 kilometres per second, which seemed…a lot like thrust.”
A prototype has yet to be built but the concept represents an advance on what NASA already uses with satellites called pulsed plasma thrusters (PPTs). These low-powered electric thrusters use two high voltage electrodes placed close to the propellant source. When the fuel, usually xenon gas, is ignited the thrusters produce a small plasma discharge guided by the electric fields to discharge out the back of a thruster. The amount of thrust produced is small, no more than you blowing on a piece of paper. But over time, if operated continuously, a PPT can attain speeds of near 7 kilometres per second.
What Ebrahimi is proposing replaces the electrodes with magnets and uses almost any type of gas, not just xenon, as the propellant. The magnets concentrate and channel the gas plasma to form bubbles containing lots of kinetic energy which can propel a rocket at speeds minimally exceeding 72,000 kilometres (44,730 miles) per hour. Note I said minimally, equivalent to 20 kilometres (12 miles) per second. That’s almost three times faster than existing chemical rocket propulsion systems today. But it gets better. By adjusting the magnetic field Ebrahimi’s plasma rocket can theoretically reach speeds of 1.8 million kilometres (1.1 million miles) per hour, 70 times faster than what Elon Musk’s Starship can produce to fly to Mars. Musk’s rocket journey of six to eight months would be dramatically reduced to as little as a couple of weeks making it possible to visit Mars not just when it is conveniently aligned with Earth, about every two years, but regularly.
Ebrahimi describes her propulsion system in an article that appeared in December of last year in the Journal of Plasma Physics. She argues that the only practical form of propulsion that will allow humans to explore the Solar System beyond the Moon and Mars is a rocket that uses magnetic reconnection, the physical process that occurs in the interaction between highly conducting plasmas and magnetic fields to produce kinetic energy — velocity. This is the energy behind coronal mass ejections erupting from the Sun’s surface at high speed.
Ebrahimi calls the output of her engine (see schematic below), Alfvenic, named after Hannes Alfvén, who first described waves produced by the interaction of magnetic fields with plasmas or fluids.
With this type of rocket engine, Ebrahimi envisions humans exploring the Solar System with little fear of exposure to cosmic radiation. She believes we could even go interstellar reaching solar systems within a few light-years from ours. She hopes to build a prototype soon.
]]>That is if you are convinced by the recent announcement from researchers in China who have been working with sheep to produce healthier meat alternatives for Chinese consumers. In support of this effort the Beijing Genomics Institute in Shenzhen has created genetically modified sheep by introducing a gene into a donor cell. The gene is linked to the natural production of polyunsaturated fatty acids.
The donor – Chinese Merino sheep.
The gene – from a roundworm, C. elegans.
The fat that this modified sheep produces is like the fat in nuts, seeds, leafy greens and fish. Lots of testing is planned before this new variety of sheep gets introduced for human consumption.
Genetically modified or GM foods are labelled transgenic. Most countries to date have concerns about the safety of such food products.
Biomedicine Update: Tiny Robots Make Beating Heart Operations Safer
Boston Children’s Hospital has developed a new set of cardiac surgical robotic tools. They are millimeters in size and can be deployed through small incisions using a curved-metal-tube.
Current minimally invasive surgery uses catheters for implanting valves, stents and butterfly clamps for closing holes in the septum, the central wall that separates the chambers of the heart. But catheters don’t give surgeons any feedback when exerting force during a procedure.
These new millimeter-scaled robots containing tiny gears, chains and pulleys (see the image below), on the other hand, do. In addition to hole closures micro-robots have been developed for excising heart tissue that is impeding heart function. The robotic devices are being perfected using animal studies before deployment in the hospital’s surgical suite.
Geo-engineering Update – Consequences When Compensating for Global Warming
Researchers studying how to reduce sunlight in an atmosphere richer in carbon dioxide (CO2) to mitigate the greenhouse effect have created models that demonstrate geo-engineering isn’t easy.
The models attempted to:
In the model the hypothetical scenario had four times the CO2 of our pre-Industrial atmosphere. The results saw an overall global decrease in rainfall. The decline was 15%, approximately 100 millimeters (around 4 inches) per year in much of North America and northern Eurasia. In the Amazon of central South America rainfall decline by more than 20%.
Although the climate model was not intended to reflect an actual geo-engineering project, decrease in rainfall was not an expected result because previous climate models designed to deflect sunlight indicated increased crop yields through increased cloud cover and precipitation.
The study did not focus on ocean acidification resulting from the release of significant amounts of sulfur dioxide.
Space Update: Australian National University to test Plasma Rocket Designs
The Mount Stromolo Observatory in Australia is to be home to a Space Plasma Power and Propulsion Laboratory that will look at using fuel other than noble gases like xenon as a power source for plasma rockets.
The ability to use any type of propellant makes plasma rocket technology far more flexible, liberating it from reliance on expensive fuels. The plasma thruster and testing facility should be in place by the middle of 2013.
If you are unfamiliar with plasma rocket technology please read the content of one of the more recent blogs on this site looking at new rocket propulsion technologies.
Transportation Update: Commercial Sub-orbital Flight Services on the Horizon
Last week’s successful conclusion of the Falcon 9 launch of Dragon and its docking and return from the International Space Station has had interesting consequences for Earth-bound travellers. Suddenly there is renewed interest in sub-orbital flights to cut down the time it takes to fly between remote destinations here on Earth. Hypersonic sub-orbital flights between Sydney, Australia and New York will soon be within our reach say the pundits. And venture capitalists are taking a renewed interest in what is seen as the next phase in the development of commercial aviation.
Virgin Galactic is one of a number of companies that plan to offer these types of terrestrial flights taking as little as an hour to connect travellers to major commercial destinations. Virgin already has a list of over 500 passengers signed up for its sub-orbital tourist flights including celebrities like Ashton Kutcher.
