Filament (User)

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The Filament control panel displays settings and allows control over the filament (W/LaB₆) and high tension settings.

 
     Filament

The Filament button switches the heating of the filament on or off. The filament button has three possible settings:

• The filament is enabled but off : the button is 'normal' grey. The Heat to step value must be other than 0 (otherwise pressing the button has no effect).
• The filament is on : the button is yellow.
• The filament is disabled : the text in the button is grey. This typically occurs when the vacuum is not ready or the high tension is off.

When the filament heating is switched on, the filament is heated to the value indicated in the Heat to: spin-enter-edit control at a rate defined by the delay steps.

 
     Heat to

The Heat to spin buttons change the filament heating step to which the filament will be heated. If the filament is off (Filament button is gray), any changes have no direct effect. If the filament is on (button yellow), the changes (defined by the spin buttons) are implemented once the Enter button has been pressed.

Changes in heating current are executed with the delay steps defined.

The Heat to value cannot exceed the filament limit set.

 
     Heating step display

A progress bar displays the current value of the heating as a fraction of the total range. The total range is determined by the filament limit setting.

 
     Emission step

The Emission Step spin buttons change the emission settings of the gun. Press the Enter button to set the new value. Possible values are in the range 1 to 6. In general, the emission should be set so as not to exceed normal filament emission values (typically 10 uA for LaB₆, 50 uA for W).

At lower high tension values, the emission value must be increased to keep the emission current similar to the values obtained at higher high tension settings.

 
     Emission display

The emission display shows the current value of the emission current.

 
     High tension

Pressing the High tension button switches the high tension on and off. The high-tension setting is is the one shown in the drop-down list box on the right. The High tension button has three possible settings:

• The high tension is enabled but off : the button is 'normal' grey.
• The high tension is on : the button is yellow.
• The high tension is disabled : the text in the button is grey.

The high tension is enabled through the High tension enable button on the System On/Off Panel.

 
     High tension setting

The high tension setting is by clicking in the drop-down list box and selecting the required setting (a range of fixed settings, comprising 20, 40, 80, 120, 160 and 200 kV).

 
     Status

The status displays (when relevant) waiting time before the filament has reached the status requested by the operator.

Page last modified on 11/26/01