Download - CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

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Page 1: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

CLIC main beam quadrupole alignment using cam movers

Juha Kemppinen

23.01.2018

Page 2: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

CLIC CDR (2012)

MBQ pre-alignment requirement

• Magnetic centres of MBQs situated on any 200 m section of the linacsshall be within a cylinder with a radius of 17 µm in 1 σ

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• Tolerance for a single MBQ misalignment is:• x- and y-offsets at both ends of the MBQ: +/- 1 µm• Roll: 100 µrad (table 2.13 of CLIC CDR)

Page 3: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

MBQ stabilisation and adjustment

• 5 DOF adjustment system takes care of the alignment

• To reach CLIC luminosity requirement, the MBQ needs to be stabilised to within• 1.5 nm in vertical and 5 nm in horizontal

• The piezo stabilisation stage imposes a stiffness requirement to the alignment stage• First eigenfrequency > 100 Hz

• In CDR and this presentation, a system based on eccentric cam movers is proposed for the 5 DOF adjustment system

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5 DOF adjustment system

Stabilisation and nano-positioning

MBQ

Page 4: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

Cam mover

Single cam and follower 5 DOF system

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6 DOF possible with an additional cam and re-organisation of interfaces

Page 5: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

Test setup

• Wire Positioning Sensors (WPS) are mounted on ceramic balls through kinematic couplings (conical – flat – conical chamfer)• Sub-micron repeatability

• 8 offsets (WPS 1 – 4) are used to calculate relative orientation in 5 DOF

• 16 offsets and a laser tracker are used to calculate module absolute position

Performance

Resolution 0.1 µm

Linearity 1 µm/mm (1 σ)

5 DOF relative 3 µm (1 σ)

5 DOF absolute 5 µm (1 σ)

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See presentation of Anna Zemanek!(case two wires with cWPS)

Page 6: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

Positioning performance

• Type 4 cam movers were able to position the mock-up chassis within 1 µm (in relative) with iterative process already in 2012

• Z. Kostka created a positioning algorithm with which the MBQ can be positioned within 1 µm in absolute (assuming the feedback is ideal) in one movement

• The positioning algorithm calculates part of the whole trajectory before movement and updates the trajectory during motion • The trajectory points are calculated using

a kinematic model and corrected based on WPS feedback

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Page 7: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

Stiffness• Previous prototypes concentrated on the positioning accuracy (movement resolution)

• Especially type 1 cam movers are difficult to make stiff (lack of space)

• New prototype is being manufactured to tackle the problem

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Page 8: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

Stiffness

• Bearing around the eccentric part removed

• Shaft is thicker

• Back-to-back configuration of tapered roller bearings (radial and axial stiffness) on one side of the eccenter and radial roller bearing (radial stiffness) on the other.

• Rotational stiffness from a worm gear through a belt drive

• Crowned eccenter in order to ensure Hertzian contact with relatively large contact area

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Page 9: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

Stiffness

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• The eigenfrequencies and corresponding modes of the MBQ depend on:

1. Structure of the MBQ and the stabilisation system2. Structure of the cam movers3. Interface between ground and cam movers4. 5 Hertzian contacts between the cam movers and the followers

• The Hertzian contact stiffness depends on:• Geometries• Materials• Contact force• Coefficient of friction (tangential stiffness)

• Adding contact force increases the stiffness…

• … but increases the friction force, which deteriorates movement resolution• Especially “stick-slip”

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2

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Page 10: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

Stiffness – resolution trade-off

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• It is very hard if not impossible to formulate the stiffness – resolution trade-off only theoretically

• The new type 1 prototype will serve as an experimental setup• Possibility to adjust the pre-load between 1 and 4 times

the weight of the MBQ and the stabilisation system by adding or removing springs (mid-travel)

• The test plan is:• To perform experimental modal analysis with 3 different

pre-load configurations• Test movement resolution and positioning accuracy with

the same configurations

• It would be interesting to compare the EMA results to PACMAN results where there is no alignment stage

Page 11: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

Expectations and threats

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• Movement resolution gets lower as pre-load gets higher, but• As long as there is enough torque, accurate

positioning can still be possible with longer movements (static vs. kinetic friction)

• The 100 Hz goal seems impossible to achieve with type 1• But maybe it’s possible to adapt to it if the first

eigenfrequency is sufficiently close to 100 Hz and its mode is known

• By combining the tests and FEM, it should be possible to estimate how the 100 Hz goal could be achieved

Page 12: CLIC main beam quadrupole alignment using cam movers€¦ · alignment using cam movers Juha Kemppinen 23.01.2018. CLIC CDR (2012) MBQ pre-alignment requirement •Magnetic centres

Thank you!