Software Manual Section 07

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Stability
	Introduction This program is used to monitor the primary or secondary beam current over a certain amount of time. It is very useful during the tune-up of the instrument or while the primary ion source is starting up.
	Signal From this pull-down menu you can choose the signal to be monitored. The options are secondary ion count rate in the electron multiplier, secondary ion 'count rate' in the Faraday cup and primary beam current in the primary Faraday cup.
	Mass When a secondary ion signal is selected, a mass number can be entered here. For primary beam stability, this control is disabled (i.e. grayed out).
	Time Enter the desired duration of the measurement here and select a time unit. In the example shown the measurement will run for 30 seconds. For an open-ended measurement enter "0" and the stability program will run continuously. This time can also be changed while a measurement is running.
	Step (s) Enter the counting time for each measurement step (in seconds) here. A value of "1.0" means that each measurement of the signal will be 1 second long. No matter what is selected here, secondary ion signals will always be shown in the plot as counts/second. Note that this number will always be the 'net' counting time and that a measurement consisting of 30 individual 1-second measurements of the EM signal will actually be somewhat longer than 30 seconds because the computer needs some time in-between to read and process the data.
	Start Click here to start a measurement. The "Start" button will change to "Running" for as long as the measurement is active.
	Abort This button will only show up during a measurement. Clicking "Abort" will immediately stop a measurement. More precisely, the measurement will be stopped after the current measurement step. If a long counting time per step is selected, you may notice some delay.
	Horizontal Axis The numbers on the horizontal axis will always be in the same units (seconds, minutes, hours, days) as selected for the total measurement time. Different units can be selected while a measurement in running and the axis will change accordingly.
	Vertical Axis There are different controls for the vertical axis: "Auto Scale" automatically adjusts the Y axis to show the entire range of measurements and "Manual" can be used for a customized range. It is also possible to switch from "Linear" to "Logarithmic" scaling. The four up/down buttons next to vertical axis can be used to change the upper and lower limits of the displayed range. Pressing one of these buttons will switch the scaling mode to "Manual".
	Cursor This display has two different modes of operation: During a measurement it displays the current time since beginning of the measurement (in the same units as the horizontal axis) and the last reading of the signal. For primary beam measurements (as shown here) the current is displayed in two different ways. Secondary signals are displayed both as counts and as counts/second. After a measurement, a vertical line (the cursor, hence the name of this display) will show up in the plot area. This cursor can be moved around by just clicking somewhere in the plot area. The displayed time and signal values are always from the current position of the cursor. It is thus possible to get exact numerical information for any part of the plot.
	Curve Statistics Some basic information about the current curve is shown here. The maximum and the minimum value of the signal are given and the corresponding points are highlighted in the plot as well:
	Exit Click here to leave the stability program. If a measurement is running you have to click "Abort" first and then "Exit".
	Print & Save Buttons for printing the plot and saving the data to a file still have to be added.

FJ Stadermann	Back to Top	Next Section