Exercise #2

In this second module, you will examine the relationship between the total input power and output fusion power and determine the efficiency for both deuterium-only plasmas and plasmas that are equal parts deuterium and tritium. All plasmas are in low mode confinement. As part of this process you will first need to analyze a variety of graphs to determine the best time at which all plasmas should be evaluated.

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The shot numbers you will be using for this exercise are for power scans in low mode and are as follows:

Total Input Power Scans in Low Mode
Deuterium only Deuterium-Tritium
88603 88898
88597 88896
88578 88865
88574 88742

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Step 1

Input all of the deuterium only shots and plot Energy Confinement Time and Stored Energy. Looking at both graphs, can you identify the time interval during which there is an increased level of Stored Energy in the plasma? Notice that this time interval corresponds to a relatively flat line on the Energy Confinement Time graph.

Step 2

For the same shots, plot Energy Confinement Time and some of the other input data types (e.g. Plasma Current, Beam Power, Total Input Power, Central Electron Density, Toroidal Magnetic Field). Looking at these graphs, try to narrow down the time interval you identified in Step 1. Try to identify a specific time at which data on all or most of the graphs looks good. Remember, only the total input power is supposed to increase in each shot. You want to choose a time where all other input parameters are approximately equal.

Step 3  

Using just the deuterium shots, plot Energy Confinement Time and Output Fusion Power. Identify two shot numbers that produce the most and least amounts of fusion power at the specific time you have selected. Record the time and the shot numbers in the Data Table below.

Step 4

Using only these two shots, look at Total Input Power and Output Fusion Power for the specific time you have selected (you may want to change the time interval when you plot the graphs to get a closer look at the graphs). What is the maximum power output for each of your deuterium shots at that time? What is the corresponding input power at that time? Calculate the efficiencies for each of your shots (ratio of power output to power input). Enter your data and calculated efficiencies in the Data Table below. Then calculate the average efficiency and enter that also.

Step 5  

Repeat steps 2-4 using just the deuterium-tritium shots. Enter your data and calculated efficiencies in the table below.

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Shot Number
(black line)
(red line)
(green line)
(blue line)
(magenta line)
Data Type (Top Plot)

Data Type (Bottom Plot)

From seconds to seconds

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Data Table

Record your data here. This table is to help you keep track of your data and calculations. It will not be submitted. You can enter any number, text, or special characters.

Plasma Time (sec) Shot Number Output Power (MW) Input Power (MW) Efficiency (%)
Avg Efficiency
Avg Efficiency

Ready to answer the questions on page 2?


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