Contents of Vol.10,No.4

1. Klystron/Subbooster Phasing
2. Orbit Bump Knobs
3. New Software Knobs Panel
4. Micro Information
5. PEPII Fast Feedback Loop-Select Panel

Page contact and owner at end of this issue.

Klystron/Subbooster Phasing

October 1, 1997

In order to better monitor and control the phases of klystrons and subboosters in the linac, the Klystron Golding facility has been substantially rewritten. However, the conceptual core of the procedure is unchanged:

1. Configure a measurement. Choose the target device whose phase is to be measured; also choose a pattern of phase set points. Select a means of measuring energy (the analyzer).
2. Acquire the data. Move and read back the phase of the device while also measuring energy.
3. Find the proposed change. Fit energy versus phase with a cosine to find the phase at which energy is at its peak. Compare to the phase expected to give peak energy.
4. Implement the change (optional). If the fit is satisfactory, change the GOLD database secondary for the device. GOLD is an offset used by the micro in maintaining the device's requested phase, PDES.

The new klystron golding panel may be reached from Klystron Index. The remainder of this article will describe (briefly!) the most significant new features. A more comprehensive description of the functionality of the package can be found in the panel help.

Dithering

The original Klystron Golding package used Correlation Plots to do its data acquisition. In the new package this is still the case for klystrons, but for subboosters data acquisition is typically done by dithering the phase of the subbooster on a pulse-to-pulse basis while reading out several BPMs. For each pulse the data from the BPMs are then fit to calculate energy. Dithering is fast (a few seconds per subbooster at 120 hertz) and tends to disrupt the beams less than the Correlation Plots acquisition.

Files

All data taken are written to files, one per phasing measurement. Old data may be recovered at any time for further analysis. The buttons for restoring old data, along with a few other diagnostic function buttons, may be found on the sequel to the main golding panel.

New Displays

The amount of information needed to specify a measurement configuration for a range of klystrons or subboosters is large, and differs somewhat depending on the mode of data acquisition. It is not possible to show all the relevant parameters on buttons, so there is a new display for this purposes, invoked with

The old Z-plot display has been replaced with a single plot showing proposed change with an error bar for each device in the current range for which a measurement has been done (or restored from a file).

The Text Display has a line of text for each measured device in the current range, including the proposed change to GOLD and several quantities useful in determining whether a given measurement and fit are good, hence whether the proposed change should be implemented. Some advice on how to evaluate these quantities may be found in panel help for

Orbit Bump Knobs

October 13, 1997

A new orbit bump generation facility, currently just for the PEPII, is available from the Bump Knobs Panel button on the PEP-II Beam TuneUp panel. The latter is reachable from the PEP-II Index Panel.

To create an orbit bump knob enter its location, e.g. a BPMS, its plane of action (x or y) and the bump type using the

buttons. Then cycle

to AUTO and use

to calculate a corrector multi-knob file and to assign it to a knob.

The Locatn ``button'' will help one to choose a valid bump reference device.

The ``Bump Type'' button has 5 choices; 3 closed bump types and 2 unclosed, ``x'' and ``x prime'' bumps:

1. 3CorPos: A Three corrector positional bump
2. 4CorPos: A Four corrector positional bump
3. 4CorAng: A Four corrector angle bump.
4. 2CorPos: Two corrector positional, ie an ``x'', or ``displacement'' bump
5. 2CorAng: Two corrector angle, ie an ``x Prime'' bump.

A ``positional'' bump knob varies the position whilst trying to maintain the angle as much as possible.

The Comp & Assign Knob button will prompt for the number of a knob on which to assign the computed multi-knob. The units of the multi-knob display are millimeters for a position bump, and milliradians for an angle bump. The sensitivity of the multi-knob is initially set to 2 turns per millimeter for a position bump, and 5 turns per milliradian for an angle bump.

The Corr Select button cycles between USER and AUTO. If AUTO is selected, appropriate correctors for the location, plane and type of the bump are chosen by the scp at the time that the Comp & Assign Knob button is pushed. One can see the correctors that were chosen by visiting the ``Bump Correctors'' panel, described below.

If USER is selected, one has to choose the correctors that are to be used before hitting the Comp & Assign Knob button. Choose correctors with the ``Bump Correctors'' panel. That panel is accessed via the

and it shows which correctors are selected for use on each micro. It includes a scheme for cycling back and forth between the micros of the ring allows one to look at the correctors for each micro.

Some restrictions on the positions of the correctors relative to the bump reference are checked at the time that the Comp & Assign Knob button is pressed.

• For a two corrector bump both correctors must be ``upstream'' of the bump reference location
• For a three corrector bump there must be one upstream and one downstream corrector. The location of the middle corrector relative to the bump reference is not checked
• For a four corrector bump, 2 correctors must be upstream and 2 must be downstream.

Changing any of the parameters of the bump, such as it plane, type, etc, de-selects all the correctors, though that is only pertinent if corrector selection is in USER mode.

This software is currently configured to compute only PEPII bumps. As such, only devices that are in the HER model (MODL_58 display group) can be entered as the bump reference device. We do envisage soon generalizing this software to the rest of the accelerator complex.

New Software Knobs Panel

October 7, 1997

The SCP software knob facility has been completely re-designed and re-written. The old pop-up knobs panel has been replaced by a new one which is created as a separate window when a SCP is started. This knobs panel initially appears as an icon. To use the panel, expand the icon to a window, and when you have finished using the knobs you can iconify the panel as you would any other SCP window.

The panel consists entirely of ``Motif'' widgets and you interact with them as you would any ``windows'' type widgets. Several knob functions are controlled by widgets with drop-down lists of options which can be selected. Some of these also include a text area showing the current knob value. These can also be directly edited to enter any desired value. This helps keep the knobs display as simple as possible.

If you are using the software knobs for the first time, please turn on the help window (with the upper right hand button) and review the features of the panel. You may navigate through the help file with the scroll bar or the Prev/Next keys on the keyboard.

Because the knobs panel is a separate window which always exists in either an iconified or expanded state, it is no longer necessary to remember and use a combination of mouse buttons to pop up the panel.

Likewise, when the panel is used there is no longer a need to use the center mouse button to captively ``attach'' the mouse to a knob so that the knob can be changed. The new panel has a scale with a slide which provides this capability. The slider can be dragged, single stepped, or continuously stepped to change the knob value.

When using the old panel while the mouse was ``attached'', certain types of errors could have resulted in an inoperative mouse, requiring the reboot of the workstation or NCD. There were also instances of ``runaway'' knobs which could not be stopped. Now the mouse is never captive and is always visible.

New Features

The new panel also has some new knob features:

1. You can type-in a new setpoint for the assigned device in addition to ``moving'' the knob.
2. You can type-in a gain value in addition to choosing one of a set of standard gains.
3. You can deassign one or all knobs. Any deassigned knob will disappear from the window. The panel resizes to show only knobs which have been assigned to devices.
4. The endpoint values of the current range of the knob are shown at the ends of the scale.
5. Using the center mouse button you can ``click'' the value of the knob directly to where the cursor is positioned in a single ``step''.
6. You can use the keyboard arrow keys to move the slider. The keys can be enabled only for one knob at a time. For safety, the keys can be disabled for all knobs.

Help

Rather than being presented on the SCP's graphics screen, the help for the panel is now presented in a separate text window. This eliminates the need for paging buttons and gives the reader the ability to read the text without page breaks.

Errors

If you make an error while using the panel, a one line error message appears in a bar at the top of the panel. This saves the user from having to find the message window, making it visible, and then going back to the knob panel to continue. The error text is surrounded by a colored outline according to the severity of the message. When the user next clicks on the panel the bar will turn black again.

Clicking the mouse on the bar at anytime will cause a text window to pop-up which contains the current or most recent error and may contain more detailed or contextual information than the one line message presented in the status bar.

Micro Information

October 7, 1997

It is now possible to display Available micro idle time, CAMAC memory pool, and RMX memory pool information using the History Buffer facility. The displays can be accessed by selecting the INDEX-> NETWRK Index -> MICRO DIAG-NOSTIC and the MICRO HISTRY BUFFER touch panels.

Select the desired micro using the ``ENTER MICR'' button. Select one of the three history buffer displays using the ``CPU IDLE HISTRY'', the ``CAMAC POOL HISTRY'', or the ``RMX POOL HISTRY'' buttons. Generate the display using the standard History Buffer ``PLOT'' buttons.

The ``CPU IDLE HISTRY'' displays the available CPU processing time in units of 0 to 100 percent. The ``CAMAC POOL HISTRY'' displays the memory available for CAMAC operations in units of bytes. The ``RMX POOL HISTRY'' displays the memory available for general micro software usage in units of bytes. In general the lower the number on any of these displays the closer the micro is getting to running out of a critical resource.

Nominal values vary between micros depending upon the type of micro, the amount of memory installed, and usage factors such as the number of fast feedback loops running, beam rate, and active BPM activity. Typical CAMAC memory pool values should be approximately 600K bytes for all three standard micro images. Typical RMX memory pool values are 1M byte, 5M bytes, and 29M bytes for the STD4MBL, STD8MBL, and the EPCMBL micro images, respectively. Typical CPU idle times for fast feedback micros may be less than 30 percent while other micros should be greater than 90 percent.

PEPII Fast Feedback Loop-Select Panel

October 6, 1977

A new fast feedback loop group has been added for PEPII and all PEPII fast feedbacks have been moved to the new group from their previous locations in the LINAC or MISC groups. Furthermore, the moved PEPII loops are accessible only when the user enters the Fast Feedback main panel from the PEPII Index panel; they are no longer accessible if the user enters the Fast Feedback main panel from the SLC Index panel.

When the user enters Fast Feedback from the SLC Index panel, the familiar eight loop groups are indicated on panel buttons:
GUN, INJECT, DAMP RING, LINAC, EAST END, LASERWIRE, DIAG, MISC

However, when the user selects the LINAC or MISC group, he will not see the PEPII loops which were previously part of those groups.

When the user enters Fast Feedback from the PEPII Index panel, six loop groups are indicated on panel buttons:
GUN, INJECT, DAMP RING, LINAC, PEPII, MISC

When the user selects the PEPII group, he will see all the PEPII loops, which are accessible only from this panel. All other groups on this panel contain loops identical to those accessible via the SLC Index panel.

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