YASP Steering Program User Guide

Transcription

1 YASP Steering Program User Guide Jorg Wenninger Version 0.5 /

2 Table of contents 1. Introduction Application Starting up Acquisition setup User selection Acquisition parameters Acquisition settings (Gains ) Dataviewer DV colour coding DV plot limits Zoom Orbits and references Catalog Elements status control Status Control Tools Detailed Status Control Steering General steering Bumps Trims Simple Trim Expert Trim Trim incorporation Response measurements SPS Power Converter and Magnet Exceptions... 21

3 1. Introduction YASP (Yet Another Steering Program) is a beam steering application for orbit and trajectory correction and analysis. YASP is JAVA based application and although it is designed to run in the context of an LSA (LHC Software Application) control system, YASP may be run in standalone mode without reference to any external control system. YASP has a light-weight interface to MAD8/MADX through compatible output file formats. 2. Application The YASP application is composed of a main user interface window and a JAVA Dataviewer display window. While the user interface window opens program startup, the Dataviewer (DV) only appears once a valid context, consisting of machine settings, associated USER and optics, has been selected. The main window is composed of a menu bar (top), a tool and information bar and a main panel split into 3 sections: o On the left a panel is dedicated to the position acquisition.

4 o In the middle a tabbed-panel is holding the interfaces for most steering options (except the ones that are too large). o On the right a console is used to display messages and information. 3. Starting up Depending on the machine and the context variable set by the console manager, YASP will try to bootstrap its configuration by looking for appropriate settings and configurations in the LSA DB. If the context is properly set and the search successful YASP will be initialized automatically. If no (valid) context is pre-set in the console when YASP is launched, the main window is empty and the only menu available in the menu bar is the File menu. In the File pull-down menu, two options are available, namely Online Context Selection and Offline Context Selection. The context selections are used to initialize YASP for a given beam and machine. Offline context is used when the program is run in standalone mode, without any connection to the LSA control system and to a real beam. This mode is useful for setting up new machines, working offline on data or for studies and design of non-existing machines. Online context selection is used to select the USER and the settings for trims. A click on Online Context Selection pops up the following window, here an example for LEIR. First a SuperCycle must be selection (left menu), then a Category (LEIRRING in this example) and finally a Beam Process. For LEIR only one beam process may be selected. No Parameter (right side) has to be selected. A click on Commit Context Selection triggers a program init from the DB for the selected context. The init will succeed provided all required DB configuration is available for the selected SuperCycle, Category and Beam Process combination.

5 4. Acquisition setup 4.1 User selection When the context is loaded, the USER is set based on the DB information. In the case where the USER played by the timing system is not consistent with the DB information (which should normally NOT happen), it is not possible to acquire position data. In such a situation it is possible to FORCE a different USER by selecting option Acq. Configuration in the pull-down menu Acq&HW in the top menu-bar. The following panel appears in the central tabbed-panel. The USER may be changed by editing the appropriate text-field, followed by a click on the Set User button. The Set Default button restores the initial DB configuration. Caution: When the USER is forced in such a way, trims on the orbit correctors may lead to unpredictable results and possible messing up of settings since the cycles that are played may not be consisted with the cycles that are trimmed. It is very likely that the user will observe that trims do not seem to affect the beam at all! Please use this possibility only to measure orbits, never to trim! 4.2 Acquisition parameters Acquisition parameters are defined on the left side of the main panel. A click on the Acquire button (top) initiates either a Single or Repeated acquisition, depending on the selection of the radio-button Single / Repeat. The acquisition time is set by clicking on button xxx ms: a popup appears where the acquisition time may be set. The time limits are determined from the properties of the selected cycle or beam process. The following boxes may be checked (some are activated by default): o Checking the box Read CODs triggers a readout of the orbit corrector settings from the DB (not from HW!!). Checking this option is recommended. o Checking the box Autosave triggers an automatic save of each acquisition to file in the predefined save path. Usually a default file path for storage is predefined for each machine. The path where files are saved is defined in pull-down menu File, option Save/Read Data Files On the panel that appears in the central tabbed-panel select

6 the Save As option and set the path that is defined in the panel. This panel may also be used to save files individually with user selected names. o Checking the box Simulation generates simulated orbits for tests. When the simulation mode is activated the color of the Acquire button changes to RED. Simulations are affected by parameters that may be set from pull-down menu Steering, option Simulation Setup. The panel that appears in the central tabbedpanel is shown below. The user may set the simulated rms kick strength, the number of kicks, a possible rms momentum offset, the monitor noise and the loop time for repeated simulations. o Checking the Difference box activates the display of the difference between an orbit and the reference orbit, instead of the absolute orbit. The button Load Last reloads the last acquired position data.

7 4.3 Acquisition settings (Gains ) Special settings like BPM gains may be set from pull-down menu Acq&HW, option Acq. Settings. Clicking on the Set or Get buttons triggers a send to or read from HW action. 5. Dataviewer A large number of so called Views (equivalent to a plot) are available in the Dataviewer. A list is shown in the figure just below. The list appears by clicking on the Views button on the top left of the DV.

8 For the user s convenience short cuts to the most important views are provides in the toolbar of main window. The 7 icons to the left provide direct access to the DV Views: o o o o o o o Position H + V Monitor & Kick Settings H Monitor & Kick Settings V Intensity/Sums Monitor Results Corrector Results Bump Shape. A click on one of the short-cuts changes the view that is displayed in the DV automatically. 5.1 DV colour coding The colour coding of the standard DV elements like position monitors and steering magnets is uniform for ALL machines. I have selected the following colour coding rule, shown in a panel available from pull-down menu Options, option Colors. Monitors : o Green : status OK o Orange : HW error bit set o Red : disabled by operator (user) o Magenta : reference orbit Correctors : o Blue : status OK o Orange : HW error bit set o Red : disabled by operator (user) o Magenta : reference settings 5.2 DV plot limits The plot limits for all position plots are identical to avoid confusion due to auto-scaling limits. The same applies to corrector settings plots. The limits may be set from pull-down menu Options, option Dv & Plots. This option adds the following panel to the central tabbed-panel. The numbers in the text fields are the limits (+-) for the monitor and the corrector setting plots. Changing the values automatically updates all plots.

9 5.3 Zoom A zoom option is available on each plot by clicking and selecting the area with the left mouse button. A click on a plot with the right mouse button leads to a zoom out (or zoom back if the plot has been zoomed in). Please note that on Linux system it may be necessary to activate a plot before performing actions like zooms by clicking on the bar above the plot that is shown below. 6. Orbits and references YASP is holding in memory at any time a number of orbit (or trajectory) data sets for display. They are accessible through the selection Load Data of the main tabbed-panel (this option is ALWAYS present). The data sets that are available are: o The active orbit the orbit that is displayed. o The last acquisition the last orbit that was acquired. o The reference orbit (if set). o The predicted orbit from the last H correction, from the last V correction and the combination of the last H and the last V correction. To load any of those sets into the DV, select it in the list and click on Load Selection to DV. Note that the selection also becomes automatically the active orbit (by definition the one in the display). Handling of reference orbit is possible through the selection References of the main tabbed-panel (this option is ALWAYS present). The same selection of data sets is available than for the previously described option. Selecting one of the elements of the list and clicking on Selection Reference loads the selection as reference data set. The reference may be displayed together with the active data set by checking the box Display Reference.

10 The button From Catalog opens a window with a catalog of reference orbits (if the catalogs is defined) 6.1 Catalog The reference catalog may be used to store orbits permanently or just temporarily. It is a file-based catalog with a simple header file that describes the entries. Clicking on Add Entry adds a new entry with a default name/comment. To change the name, simply type the new name in the appropriate field. To act on a given entry, it must be selected by clicking on it with the mouse. It is then possible to delete it, to load it as reference and display it in the DV or to simply show the data set header information.

11 7. Elements status control Menu Status-Control of the main menu bar gives access to status control panels that are useful to enable/disable elements and view detailed status information. 7.1 Status Control Tools Option Status Control Tools provides the following panel that may be used to change the status of elements using the Dataviewer. The user may select an Action (Flip Status, Enable, Disable, Zero) and a selection type (by Element or by Region). Click on the Select from DV button to activate the action. The user may then select elements (monitor or correctors) from the Dataviewer plots: the selected action will be applied to them. Note that it may be necessary to activate a view of the DV for such an action by clicking on the bar above each plot (mostly valid on Linux systems) that is shown below. 7.2 Detailed Status Control Options Edit Monitor Status and Data and Edit Corrector Status and Data may be used to edit detailed information on all elements. Clicking on those options pops up a window as shown below.

12 This frame gives access to all the data, in this example of the BPMs. For monitors it is possible to manually edit the positions (raw and corrected), the calibration factor and offset and as well the OP Enable status. The Enable status of an element is the logical AND of the HW Enable (the status flag given by the HW) and the OP Enable (the status flag set by OP). Elements where the Enable is not set (and are therefore considered as bad ) are marked with a name field in RED. It is important to note that elements that are not Enabled are not used in steering algorithms (valid for monitors and for correctors). This panel is not automatically updated when new data is acquired. Click on Refresh to update the table.

13 8. Steering The Steering menu of the main menu bar gives access to all options related to steering. The available options are: o General Steering: main global steering algorithms like MICADO, SVD o Threaders: first turn or long transfer line threading algorithms. o Bumps: bump toolbox. o Steering Toolbox: various options like dispersion calculation, harmonics (to determine the integer tune and matrix conditioning (for large rings). o Simulation: simulation setting up as described previously. 8.1 General steering The General Steering option provides the following panel. In this figure the example of the MICADO algorithm is show. The plane selection is performed using the radiobuttons Horizontal / Vertical. The number of correctors is set by the user. Checkboxes may be used to activate a Bare correction (i.e. the effect of all correctors is unfolded before the correction is run), the subtraction of the effect of a momentum error (which is evaluated from the horizontal dispersion and the orbit data) or the matrix reconditioning (procedure to localize and remove orbit correctors that may lead to singular or near singular behaviour of the response matrix). Running the correction will automatically change the View of the Dataviewer to show the effect of the correction on the orbit or trajectory.

14 This view indicates the positions before correction (top), the difference due to the correction (middle) and finally the result orbit after correction (bottom). The DV view Corrector Results shows the equivalent information for the corrector kick settings. The other algorithms are run in a similar way than MICADO. For the SVD algorithm a special DV view SVD Response Eigenvalues is available to inspect the eigenvalues and eigenvectors of the SVD inversion. An example is shown below for LEIR. The top plot shows the eigenvalue spectrum, the middle plot the monitor eigenvector and the bottom plot the corrector eigenvector. The eigenvectors associated to any eigenvalue may be inspected by clicking on the corresponding point of the eigenvalue spectrum (top plot). 8.2 Bumps The Bumps option provides the following panel, with the possibility to run 3 or 4 corrector bumps. In both cases of 3C- and 4C-bumps the user may select the target element for the bump either graphically from the Dataviewer (from DV button) or from any known element in the twiss (Twiss button). The selection of correctors may be either automatic or manual. In the later case the user may select the correct number of correctors from a list. Finally the bump amplitude (and angle for 4C-bumps) may be set in mm or microns (depending on the selection of the units). Running the bump algorithm provides a similar display to any other correction (see MICADO case described previously).

15 9. Trims Once a correction has been evaluated it may be sent to the machine from the Trim menu, option Trim that pops up the following frame. 9.1 Simple Trim The simple trim is based on the default rule for trim incorporation defined in the LSA DB, see also section 9.3. The user can send a trim in different ways, incremental or absolute. The Default Trim option is to send the full correction as an increment. Alternatively the user may send a fractional trim (between 0 and 100%, option % Trim, a scaled trim using the Send Scaled option (incremental trim multiplied by an arbitrary factor) or an Absolute Trim. All trims are always given in units of the last calculated correction: 1 = full correction. A direct cancel of the last sent trim is also possible using the Cancel Last button. The button Show Trim displays the details of the strengths that are part of the trim. The button Show Incorp. Rule displays the points associated to the incorporation of the trim into the power converter functions (see also section 9.3) A status message indicates the total trim integral that has been send or an error message in case of trim failure. 9.2 Expert Trim Selecting the Expert Trim level modifies the trim panel and provides additional trim options. The first option is the possibility to apply the trim not at the time of the acquisition on which the correction is based, but at any arbitrary (but valid) time in the cycle. The second option allows the user to switch from the default incorporation rules provided in the LSA DB to a manually set Expert Rule. The rule itself is selected from

16 the incorporation rule interface, available from the Trim menu, option Incorporation Rule (see also section 9.3). 9.3 Trim incorporation The incorporation rule defines how a steering trim that is defined at a certain time (usually the acquisition time of the orbit/trajectory) is propagated backwards and forwards in time into the orbit corrector functions. Default rules are stored in the DB, usually such rules consist of a constant propagation on part of the cycle where the momentum is constant (flat bottom, flat top, transfer line) and of triangular propagation during momentum ramps. The simple trim option described in section 9.1 uses those default rules to apply trims to the magnet functions. Expert incorporation rules may be defined inside YASP to perform more subtle or special incorporation of trims. The rule basically defines the shape of the piece of function that is added to the corrector function when the trim is applied. A special panel is available from the Trim menu, option Incorporation Rules. This panel provides: o The list of default incorporation rules defined in the DB. o The list of available expert incorporation rules, including the possibility to activate a selected rule. In all cases a minimum of 2 default rules are provided. o A rule editor to modify existing rules or to create new rules.

17 9.3.1 Default incorporation rules The default DB incorporation rules can be viewed from the Incorporation Rule panel, by clicking on the Show Db Incorporation Table button which will pop up a table of rules as shown below for the case of LEIR. The DB rules a presented in the form of a table indicating the time interval within a cycle where the rule is valid (from Start to End), the rule type (TRIANGLE or CONSTANT) and the length of the ramps (In-ramp up to Start time, Out-ramp from End time). In the case of CONSTANT incorporation, the trim is applied as a constant between Start and End time, and ramped down to zero over the In-ramp and Out-ramp intervals. For TRIANGLE rules, the trim is applied in a triangular form, a ramp up over the In-ramp interval followed by a ramp down over the Out-ramp interval. This behaviour is applied to any trim between the Start and End time range of the TRIANGLE rule.

18 9.3.1 Expert rules The Expert Rule List panel indicates the list of existing expert rules. Any rule may be activated for edition and trimming (at the same time) by clicking on Select Rule. The active rule is indicated by the red color. Three different types of editable rules are available: o Triangle incorporation rules o Constant (strength) incorporation o Constant current incorporation Once a rule is activated it can be inspected and edited in the Expert Rule Editor panel. The editor can be used to change the point locations (in time) as well as the overall time offset: either the time is given in absolute cycle trim, or it may be given relative to the time of the trim that is send. The rule editor is shown below for the case of a constant rule (i.e. consisting of a main plateau). The points of the rule (time in ms) may be edited, the overall shape and meaning of the points being indicated on the right side. Clicking on Save stores the new parameters of the rule and maintains the same rule name. A new rule is created by clicking on Save as New Rule, the rule name being the text entered in the appropriate text field as shown below. Note that rule names must be unique, therefore the name field must be changed before save a NEW rule. Time selection : o When the Use relative time box is checked, the time is considered to be relative to the trim time set in the trim panel (see sections 9.1 and 9.2). o When the Use super-cycle time box is checked, then the time of the points is relative to the start of the super-cycle. This option can be used to trim from one cycle to the next. Beware however that the trim and acquisition times are always given with respect to the cycle start time. When Use super-cycle time is selected the program will automatically taken into account possible offsets of the cycle within the super-cycle and compensated for then concerning acquisition and trim times that must always remain relative to the start of the cycle. For super-cycles composed of a single cycle, there is obviously no difference between time with respect to cycle or super-cycle start. o When the neither the Use relative time nor the Use super-cycle time boxes are checked, then the time of the points is given with respect to the cycle start.

19 The constant current incorporation rule provides a means to incorporate trims with constant current as a function of momentum. The strength is scaled using the ratio of the momentum at the reference trim time (usually the acquisition time) and the momentum at the point in the cycle. This rule is applied between the Start and the End time. Beyond those points the strength is reduced linearly according to the set Left and Right point positions (see figure below).

20 10. Response measurements Automatic response measurements may be performed with YASP using option Response Matrix in menu Optics. The automatic response measurement is performed one plane at a time. The kick strength that is applied to each corrector (+ and measurements) must be set. The number of acquisitions at each setting and the number of cycles to skip when the settings are changes (from + to kick or from a corrector to the next) can be defined. The start and end corrector must be set. The response scan is started by clicking on the Start button. At the same time the acquisition of orbit/trajectory should be started in Repeat mode in order to feed the scan thread with the appropriate data.

21 11. SPS Power Converter and Magnet Exceptions This section describes special issues related to SPS dipole/corrector issues. In the MADX program the deflection signs have opposite sign for correctors (KICKER elements) and dipole (BEND elements). For a positive angle, a KICKER deflects the beam towards the left and up (looking into the direction of the beam) while a BEND deflects towards the right and down. Exceptions in the handling of steering elements are due to: 1. A number of elements are defined as dipoles (RBEND) in MADX, but have a polarity definition of a corrector magnet. 2. A number of steering elements are defined as dipoles (RBEND) in MADX and are used by the steering application. For case 1, the sign of the strength provided by MADX must be inverted, while in the other case the sign of the deflection must be changed in the steering application (through the calibration factor of the steering element).

22 Table 1 : List of orbit correctors that are declared as BEND in MADX due to a non-zero nominal deflection but that have the polarity convention of orbit correctors (Case 1). For such elements the MADX strength sign must be changed. Transfer line TT10 TT21 TT24 Element MDIV1021 MDCV1029 MDCA1030 MDLH2101 MDLH2102 MDLV2401 MDLV2402 Table 2 : List of elements that require a sign change in the steering application because of a polarity convention of a dipole/bend (case 2). Transfer line Element Comment TT10 MBIV1003 Bend MDLH1028 Corrector with bend polarity MAL1029 Bend MSI1183 Bend (septum) TT21 MBE2103 Bend MBE21306 Bend MBB2109 Bend MBB2113 Bend MBB Bend TT23 MDAV2301 Corrector with bend polarity MDAV2305 Corrector with bend polarity TT24 MSSB2204 Bend (splitter) MBB2404 Bend TT25 MSSB2117 Bend (splitter) MDLV2500 Corrector with bend polarity MDLV2505 Corrector with bend polarity MBB2505 Bend MAL2512 Bend