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TRANSP data Tutorial
Data Preparation Tutorial
 

JETDSP Tutorial

Introduction

JETDSP can perform a wide range of tasks, this tutorial introduces the main tasks starting with reading data and moving on to more complex operations. For information about how to perform individual tasks see the JETDSP manual

Reading Data

This section is concerned with getting JET data into JETDSP. It will cover the following points.
  • Reading a PPF (including ranges).
  • Browsing for PPFs.
  • Find out which subsystems to use.
  • Reading a JPF.
  • Reading a LPF.
Clear the signal list and;
  1. Read in MAGN/IPLA for pulse 50000.
  2. Read the signal corresponding to the flux from loops 5 and 11 for DDA MAGN.
  3. Read the first pair of JPFs corresponding to the KG3 reflectometer for pulse 50000. Look here to find the JPF name
  4. Read the corresponding LPF. Look here as well to find the LPF info. Note that you will need to enter the LPF diagnostic.

Plotting Data

  1. Plot all the signals, it should look like this then close the window.
  2. Plot just the two 2D JPF signals.
  3. Ensure that the signals fill the screen horizontally when plotted.
  4. Plot these two on top of each other.
  5. Change the second to a green dotted line, and give them new legends.
  6. Give the plot a sensible title, it should look something like this.

Printing

Using the plot created in the last section printing will be looked at. Note that printing on the JAC cluster uses a different series of widgets than normal IDL programs.
  1. Choose a nearby printer to send you plot to.
  2. Print the plot.
  3. Look at the options to improve the output you got.

Using Standard Sets

JETDSP uses standard sets to facilitate the setup of commonly used graphs. This is done by creating a text file based on the signals in the signal table. This standard set can then be reloaded changing the parameters (e.g. pulse).
  1. Save a standard set for the 2D PPF signals you currently have loaded, not saving the pulse.
  2. Clear the current signal list.
  3. Open the standard set for pulse 54000, adding it to the current signals.
  4. Open for pulse 52000, overwriting the current signals.
  5. Plot all the signals and reshot for 50002.
  6. Read the standard set, overlaying it for 50003 and 50004.
  7. The final plot should look like this.

TED

TED, the timeslice editor, provides a facility to mark time points of interest during a JET plasma pulse. A timeslice marking program runs automatically for each pulse, to create an automatic set of interesting timeslices for the pulse. These can then be changed or added to manually using TED. Certain PPF data for all time points selected are then automatically stored in a central database (the CPF).

Timeslice editing functions are incorporated as part of JETDSP. The manual for TED can be found at here. The following part of the tutorial will assume that the signal table is initially empty.

  1. Download the Hmode standard set to your account (see here).
  2. Read that standard set for pulse 49138.
  3. Plot the data in a timeslice editor window (read the JETPPF timeslice PPFs).
  4. Which timeslices have had reasons manually set (see here for help)? List the reasons which have been set (see here for help on how to do this).
  5. What do all the timeslice editor symbols mean? (See here to see how to get help on this.)
  6. List all other types of timeslice data which has been set for this pulse.
  7. What plasma transition has been marked at 56.94 s? In which two ways has this transition been marked?
  8. When have giant ELMS been marked as starting? How has this bee done? What feature of the data marks the start of the giant ELMS?
  9. Read through some of the possible timeslice reasons which can be set with TED. (Help on how to do this can be found here).

Close the plot. Read in the same (Hmode) standard set for pulse 54217. Add the following timeslice data by hand using TED. (Details on how to add timeslice data can be found here).

  1. Mark the start of the giant ELMS indicated by the data, in the same way as was done for pulse 49138 (ie add a MODE type point).
  2. Add an event type point to the data, with a reason (this need not be physically meaningful).
  3. Add a new timeslice, with a reason for creation of that new timeslice (again this need not be physcially meaningful).
  4. Add new reasons for an existing timeslice.
  5. Save your timeslice data to a private PPF, under your userid (see here for help).

Close your timeslice editor plot window. Then reopen the timeslice editor, but this time read in the private timeslice data you have just created instead of the public (JETPPF) data. Check that the timeslice data you added was saved correctly to PPF.

Signal Processing

JETDSP allows the full range of IDL signal processing expressions to be used. It also allows old IBM style expressions to allow compatibility with old standard sets.

The two most commonly used types of signal processing have separate menus. These are smoothing and slicing. These, along with the main signal processing dialog, are accessible via the signal processing menu on the main signal table. For this part of the tutorial it will be assumed that the signal table is initially empty.

How to slice a signal

How to slice a signal is described here.

Some 3D signals consist of several channels of 2D data. One such signal is MAGN/FLUX. This contains 14 individual 2D signals, and these can be extracted by using the slice signal dialog.

  1. Read this signal and extract the 14 slices.
  2. Which signal has the highest value and what is it?
  3. Which signal has the lowest value and what is it?

Signal processing.

  • How to use IDL expressions
  • How to use simple expressions.
  • How to add simple expressions.
  • How to write your own code.
The manual page for signal processing in JETDSP is here For a more in depth view see, here and the tutorial contained within it.
  1. The CXSM DDA contains a corrected radius. Plot the FLUX datatype against this radius.
  2. Scale the resulting signal by a factor of 5.
  3. The time for JET data always starts at 40 seconds. Shift the data so that it starts at 0 seconds
  4. Use your answer to the previous section to create a new simple expression.
  5. Read in the standard set '/home/jetdsp/.jetdsp/StandardSets/rptraining1.jss'. This is the set of signals read above.
  6. Extract the points corresponding to the second set of time values (around 56 seconds).
  7. Smooth both signals using a rectangular window of halfwidth 100.
  8. Plot the smoothed parts over the unsmoothed parts. The final plot should look like this.
  9. For the JPFs calculate A and phi as a function of time.
  10. Create a new function to normalise any signal.

Writing PPFs

To write any data to the system at JET you need to have your account modified. This should have been done to allow you to write private data already. Having read several signals and created some processed signals save these into the system as a private PPF. See here for how to save data. Reread them back into JETDSP.
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