Skip to main content
Stars and solar physics

Stars and solar physics

Web life: The Internet Plasma Physics Education Experience

02 Feb 2009
The Internet Plasma Physics Education Experience

What is it?

An educational outreach site maintained by the Princeton Plasma Physics Laboratory in the US, IPPEX features several interactive, game-like tools (applets) for exploring the physics of fusion, the doughnut-shaped “tokamak” reactors used in fusion experiments around the world, and related topics.

What are the simulations like?

Slider bars and pop-up graphs on the Virtual Tokamak applet allow wannabe fusion scientists to determine how plasma density, magnetic field and auxiliary heating in their simulated reactor will evolve over a 20 s “shot”. Once you are happy with your choices, you can fire up the tokamak and watch the program generate a time-dependent graph of how much power your reactor produces. In the Magnetic Confinement applet, the aim is to keep the plasma within the tokamak cross-section by switching magnets on and off. Additional applets appear in tutorials illustrating basic principles of physics like electricity and magnetism.

Where is the physics in these games?

IPPEX head Andrew Zwicker notes that the Virtual Tokamak runs a “fairly sophisticated” performance calculation based on a potential reactor design, albeit with a few computational simplifications. An obvious first step on the simulated tokamak is to crank all variables to their maximum values, but be warned: if you exceed the program’s limits on plasma density or temperature, then you lose control of the plasma and your “score” (a number related to the amount of fusion power divided by the heating power) drops to zero. Similarly, magnetically confining a “mildly unstable” plasma is fairly easy, but “totally out of control” plasmas are more of a challenge. A good analogy among plasma-physics insiders is that confining a plasma is like trying to hold jelly together with rubber bands, and the Magnetic Confinement applet helps drive this point home. The lessons learned are mostly qualitative, however.

Who is it aimed at?

The physics is described on a very basic level, so that even secondary-school students should have little difficulty in following it. The format of IPPEX is ideal for teachers wishing to incorporate the site into lessons on fusion or renewable energy. In addition to the applets, the site also hosts a series of pages where students can explore real fusion data from low-confinement deuterium plasmas, answer a series of questions and submit these answers to a “Fusion Wizard” for online evaluation. In a few months, live data from the laboratory’s NSTX experiment will replace the archived shots, bringing the fusion-analysis exercises even closer to “real physics”. More advanced users may find the lack of in-depth scientific explanations frustrating, but should still enjoy playing with the applets.

Why should I visit?

The site has won several science-education awards, and it is not hard to see why. The Virtual Tokamak, in particular, is surprisingly addictive and requires a fair amount of thought to master. The hints page contains a few suggestions for boosting your score (the current maximum is around 148), but for the most part it simply urges users to play with the variables in a systematic fashion — sound advice for any experimental scientist.

Copyright © 2024 by IOP Publishing Ltd and individual contributors