Nav: Home

Clarifying the plasma oscillation by high-energy particles

November 24, 2016

Background to the Research High-energy alpha particles (helium ion) which are generated by the fusion reaction that uses deuterium and tritium bear the important roles of heating plasma and of maintaining the high temperature condition which is necessary for the fusion reaction. The prediction of their behavior and their control are the keys for maintaining the fusion reaction. On the other hand, to comprehend plasma, it also is a fluid that conducts electricity. And due to the flow of electric current, because the magnetic field is generated this is called magnetofluid (magnetohydrodynamic fluid). Plasmas that are magnetofluid oscillate. When such a plasma's oscillation period and the period of high-energy alpha particles circulating inside a plasma match, there is a possibility that the oscillation amplitude will increase due to resonance. As a result, because high-energy alpha particles will escape to outside the plasma, there is concern that the performance of the fusion reactor will degrade. In order to realize the generation of fusion electricity, highly reliable predictions regarding the distribution of high-energy particles that have considered the plasma's interaction with oscillations are imperative.

Research Results

The research group led by Professor Yasushi Todo and Assistant Professor Hao Wang of National Institutes of Natural Sciences National Institute for Fusion Science (NIFS) has developed a program that can simulate simultaneously the plasma behavior and the movements of high-energy particles (The program is called Hybrid Simulation because it connects fluid and particles). From this, it now has become possible to investigate in detail by simulation the interaction between plasma oscillation and high-energy particles, which was not possible by previous methods that calculated separately the plasma and the high-energy particles. Using this hybrid simulation program, on supercomputers (NIFS's plasma simulator and Helios, of the International Fusion Energy Research Centre) we conducted a large-scale simulation of the Large Helical Device (LHD) plasma. In the LHD experiments, we are advancing research on high-energy particles and plasma oscillations using high-energy particles generated by neutral beam injection (see Fig. 1). In the simulation results shown in Figure 2, together with reproducing well the experimental data for plasma oscillations that are caused by the high-energy particles, we clarified the details of oscillations which cannot be measured by experiment as well as the interaction of high-energy particles that cause the amplification of oscillation. This hybrid simulation program is appropriate not only for the LHD but also for fusion plasma experiments in Japan and abroad. By comparison with the experimental results regarding the distribution of high-energy particles and oscillations, the reliability of the program has been confirmed. Here, by successfully reproducing the LHD experiment, we have achieved the program for the first time in the world that can simulate high-energy particles and plasma oscillations.

This research result was announced at the 26th International Atomic Energy Agency conference held October 17-22 in Kyoto, Japan.

The Significance of the Research Results Using the Hybrid Simulation Program developed by the National Institute for Fusion Science, the prediction accuracy of high-energy alpha particles distribution in fusion reactor core plasma has significantly improved. This will contribute to the proposal of highly reliable operation scenario and design of the fusion reactor. Further, this will contribute to the early achievement of the fusion reactor. In addition, from these achievements our understanding of the interaction of high-energy particles and oscillations has advanced. While the oscillations of plasma cause the loss of high-energy particles that heat plasma, the oscillations by providing plasma with energy received from high-energy particles conversely heat plasma. This physical mechanism has gained the interest of researchers, and the knowledge that has been gained through this research is concealing the possibilities of becoming a basis of research.
-end-
Vocabulary

1. Magnetofluid model: Treating plasma as a conducting fluid, this is a physical model that describes the temporal evolution of plasma density, fluid velocity, pressure, and the electromagnetic field.

2. Hybrid simulation of high-energy particles and magnetofluid: The magnetofluid model is a superlative model that can explain the behavior of an entire plasma. In research on the interaction of high-energy particles and the oscillations of a plasma it is necessary to pursue the orbit of each high-energy particle. The hybrid simulation of high-energy particles and magnetofluid is a simulation that connects physically without contradiction the temporal evolutions of the movement of each high-energy particle and magnetofluid.

National Institutes of Natural Sciences

Related Plasma Articles:

Table top plasma gets wind of solar turbulence
Scientists from India and Portugal recreate solar turbulence on a table top using a high intensity ultrashort laser pulse to excite a hot, dense plasma and followed the evolution of the giant magnetic field generated by the plasma dynamics.
Getting the biggest bang out of plasma jets
Capillary discharge plasma jets are created by a large current that passes through a low-density gas in what is called a capillary chamber.
Neptune: Neutralizer-free plasma propulsion
Plasma propulsion concepts are gridded-ion thrusters that accelerate and emit more positively charged particles than negatively charged ones.
UCLA researchers discover a new cause of high plasma triglycerides
People with hypertriglyceridemia often are told to change their diet and lose weight.
Where does laser energy go after being fired into plasma?
An outstanding conundrum on what happens to the laser energy after beams are fired into plasma has been solved in newly-published research at the University of Strathclyde.
New feedback system could allow greater control over fusion plasma
A physicist has created a new system that will let scientists control the energy and rotation of plasma in real time in a doughnut-shaped machine known as a tokamak.
PPPL scientist uncovers physics behind plasma-etching process
PPPL physicist Igor Kaganovich and collaborators have uncovered some of the physics that make possible the etching of silicon computer chips, which power cell phones, computers, and a huge range of electronic devices.
Calculating 1 billion plasma particles in a supercomputer
At the National Institutes of Natural Sciences National Institute for Fusion Science (NIFS) a research group using the NIFS 'Plasma Simulator' supercomputer succeeded for the first time in the world in calculating the movements of one billion plasma particles and the electrical field constructed by those particles.
Anti-tumor effect of novel plasma medicine caused by lactate
Nagoya University researchers developed a new physical plasma-activated salt solution for use as chemotherapy.
Clarifying the plasma oscillation by high-energy particles
The National Institute for Fusion Science has developed a new code that can simulate the movement of plasma and, simultaneously, the movement of particles circulating at high speeds.

Related Plasma Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...