HLS Monitoring System Georg Gassner SLAC MET October

HLS Monitoring System Georg Gassner, SLAC / MET October 21, 2005 · · HLS Introduction HLS Principle Types of Sensors Integration of HLS with the Undulator October 21, 2005 1 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

Hydrostatic Leveling System Introduction The free surfaces of bodies of water have been used for several thousand years as a vertical reference. The proposed Hydrostatic Level Systems (HLS) has several significant advantages over optical methods in determining height differences between two points. Some of these advantages are: No direct line of sight needs to exist Not affected by optical refraction Higher accuracy Fully automated Self calibrating Equipotential surface is the reference October 21, 2005 2 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

Motion of Earth Surface The disadvantage of using the equipotential surface as a reference is that the earth surface itself is not stable but in constant motion. Earth tides due to sun and moon Are up to 30 mm for a 123 m long Undulator Can be modeled Ocean tide loading and atmospheric loading Can reach up to 30 mm Can not be modeled October 21, 2005 3 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

HLS Principle Hydrostatic Leveling Systems are based on the principle of communicating vessels or more precisely on the equilibrium of the pressure of the fluid in the communicating vessels. This is mathematically described by the Bernoulli equation. p + r g Z = const. Dp = 0. 10 h. Pa DTemp = 1°C; Z = 100 mm => DZ = 1. 02 mm => DZ = 67 mm October 21, 2005 4 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

HLS Configuration There are two principle configurations: Full filled pipe system Faster damping time <2 min Easier installation Half filled pipe system Temperature differences do not affect the measurements Damping time ~10 min October 21, 2005 5 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

Types of Sensors - Capacitive Sensor Principle Measures the Capacity C of the System Attributes Proven to work for many years Inexpensive Precision < 1 mm Accuracy (10 mm range) < 5 mm Possibly affected by drift Absolute height measurements are only indirectly achievable October 21, 2005 6 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

Types of Sensors - Ultrasound Sensor Principle Measures the runtime of an ultrasound pulse Attributes No drift (self calibrating) Precision < 0. 1 mm Accuracy (10 mm range) < 3 mm Absolute Measurements More expensive No long-term experience (10 years) October 21, 2005 7 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

HLS measurements related to the Girder Any three HLS sensors provide independent monitoring of Height of the girder Roll of the girder Pitch of the girder The fourth sensor provides a controlled measurement October 21, 2005 8 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

Integration of HLS with the Undulator Three capacitive sensors per girder reliable determination of height, roll and pitch One ultrasonic sensor per girder Absolute measurements Calibration of the system Controlled measurements 2 inch stainless steel pipes to connect the pots for optimal damping and maintenance All sensors are connected with TCP/IP (IEEE 802. 3 af) Following a standard (off the shelf products) Power supply included Each sensor communicates independently from all others October 21, 2005 9 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

Conclusion Reliable and controlled method for monitoring heights of the girders (1 mm level small range) pitches of the girders (0. 5 mrad) rolls of the girders (2 mrad) Damping within 10 min Supplies Wire Positioning System with information to determine the sag October 21, 2005 10 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu

End of Presentation October 21, 2005 11 Internal LCLS Undulator Alignment and Motion Review Georg Gassner, SLAC / MET gassner@slac. stanford. edu