Regression of the Tokamak Fusion Test Reactor Data

tokamak.gif (53906 bytes)In this activity, you will be performing a linear regression on the data collected from the Tokamak Fusion Test Reactor. The data consists of the electron density vs. time for plasma #45,606. Electron density is a key variable in determining plasma performance; the more constant the density values are and the quicker they increase, the better the plasma is performing. Though exponential growth would provide the quickest path to extremely high densities, the volatility of the plasma and safety concerns in the plant negate this type of approach. Time represents the independent variable x, and electron density represents the dependent variable y.

Using Excel (the TI-83 is excluded from this activity because of its inability to deal with such a large data set), perform a linear regression on the data to determine how well the plasma is performing.

This data exists in two files; one is in Excel Data format and one is in Text format.

What is the r-value of the regression? What does this r-value tell you about the variance within the data set? Should this data be considered linear? Would it be good for making predictions about the electron density of plasma #45,606 for other times? Why or why not?

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Original work on this document was done by Central Virginia Governor's School students Ashley Farmer, Josh Nelson and Sara Throckmorton (Class of '98).

Copyright © 1997 Central Virginia Governor's School for Science and Technology Lynchburg, VA