# Presentation: 452560

## Studies of Single Aperture IR Quad Mechanics

_**US LHC Accelerator Research Program**_

_***Studies of Single Aperture IR Quad Mechanics***_

- _Giorgio Ambrosio__1_, Nicolai Andreev1, Shlomo Caspi2, Deepak Chichili1
- 1*FNAL – Technical Division*
- 2*LBNL – Accelerator & Fusion Research Division*

- OUTLINE:
-   = 90 mm, stand-alone collars (DC)
-   = 110 mm, collars + partial outer shell support (GA)
-  = 90 mm, outer shell support (bladders & keys) (SC)
-  “Octagonal-collar” concept (NA)
-  Conclusions and plans

## Magnetic forces

**Forces at 228 T/m (per octant)**
**24 % margin (forces)**
**90-mm 2L quad has ****23%**** higher forces than present HGQ**
**110-mm 4L quad has ****139%**** higher forces than present HGQ**

**Forces @ 228 T/m**

|  | HGQ†

(MN/m) | 90 mm
2L  (MN/m) | 110 mm
4L
(MN/m) |
| --- | --- | --- | --- |
| FX | 1.6 | 1.9 | 4.2 |
| FY | -1.9 | -2.4 | -4.1 |

- † KEK design scaled to 228 T/m

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

##  = 90-mm – stand alone collars†

**Mechanical design concept: **
_**Stand-alone collars **_
_**30-mm thick stainless steel **_
**1****st****: pole is part of the collars**
- Same design of present HGQ
**2****nd****: ring-collars (pole stays with coil)**
- Compatible with FNAL cos fabrication tech.
- Smooth transition from straight section to ends
**Criteria:**
**Peak stress in the coil < 150 MPa **
**No gaps at 240 T/m (operation + margin)**
**Max collar stress < than the yield stress**
**Max coil displacement under Fmag < 0.13 mm**

- †D. chichili, *A preliminary mech design and analysis of 2**nd** generation HGQ,* TD-02-005

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## 90-mm – stand alone collars – 1st design

**Features of the model:**
**Simulate laminations:**
- 2 collar layers
- Symmetry BC, Coupling,
**Pre-stress by azimuthal interference: 75 ********m**
**All steps analysis:**
**During collaring (max at 300 K)**
-      Keys inserted w/out force
**After collaring (spring back)**
**At 4.2 K**
**At Fmax (****240 T/m****)**

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## 90-mm – stand alone collars – 1st design

**Pre-stress drops during cooldown: **
**~1/3 is lost **
**Stress at 240 T/m:**
**< 150 MPa**
**All coils still under compression**
**Max coil displacement under Lorentz force (240 T/m):**
**129 ********m**

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## 90-mm – stand alone collars – 2nd design

**Features of the model:**
**Simulate laminations:**
- 2 collar layers
- Symmetry BC, Coupling
**Pre-stress by radial interference: 150 ********m**
**All steps analysis:**
**During collaring (max at 300 K)**
-      Keys inserted w/out force
**After collaring (spring back)**
**At 4.2 K**
**At Fmax**

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## 90 mm – stand alone collars – 2nd design

**Pre-stress drops during cooldown: **
**~1/3 is lost **
**Stress at **_**210 T/m**_**:**
**Max < 95 MPa**
_**Coil partially unloaded**_
**	**_**But pre-stress at 300 K cannot be increased**_

- Azimuthal stress distribution in the coil at 210 T/m

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## 90-mm stand alone collars – conclusions

**The 1****st**** design (pole is part of the collars) **_**meets all requirements**_
**The 2****nd**** design (ring-collars) is **_**too weak**_** and coils unload at ~200 T/m**
**Possible solutions to be explored:**
**The use of tapered keys should allow increasing the pre-stress at room temperature**
**Impregnated collar laminations should increase the stiffness of the collars****†**** **

- †I. Novitski, et al.,Common Coil Mechanical Model #1*,* TD-01-074

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## 110-mm aperture – Magnetic forces

**Forces @ 228 T/m**

|  | HGQ†
(MN/m) | 90 mm
(MN/m) | 110 mm
(MN/m) |
| --- | --- | --- | --- |
| FX | 1.6 | 1.9 | 4.2 |
| FY | -1.9 | -2.4 | -4.1 |
| FR |  |  | 2.8 |
| F |  |  | -5 |

- † KEK design scaled to 228 T/m

**1****st**** shell: ****F******** ****= 1.5 MN/m, **
**Width = 12.3 mm, **
************_****__****__** **__**= 122 MPa**_

**Bottom half of coil: F****r**** = 1.7 MN/m, **
**E****r_coil**** = 50 GPa, E****r_ins**** = 14 GPa**
**	****	******** **_****__**r = 87 **__****__**m**_** (average)**
- And this deflection is going to increase the stress in the 1st shell!

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

##  =110 mm preliminary models 

**Infinitely rigid BC on the outer surface of the collars **
**NO pre-stress**
**Material properties @ 4.2 K**

- LAPAC - Jun 17-18, 2004

## Concept for 110-mm aperture

**Very rigid structure**
_**Extra force**_** on the mid-planes in order to reduce the coil bending**
**Almost stand-alone SS collars**
- Some pre-stress by collars
**Additional force on the midplanes from the outer shell**
- Additional pre-stress _**after cooldown**_
- Rigid structure _**avoids excessive coil bending**_

**Needs:**
**Solution:**

##  = 110 mm – gap closed at 4.2 K

**Yoke with gap at 45 deg.**
**Open @ 300 K**
**Closed at 4.2 K**
**Closed at 228 T/m**
**Gap control spacers**
**15 mm SS collar ring**
**Collar-Yoke contact 0-6 deg.**
**Outer shell:**
**15 mm SS skin or**
**30 mm Al (bladders & keys)**

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

##  = 110 mm – gap closed at 4.2 K

**Acceptable stresses at 300 K, after cooldown and at 228 T/m **
**Acceptable coil displacement under Lorentz forces (Max = 120 ********m)**

********** ****at 228 T/m**

-  1st shell < 140 MPa

**Tops of shells are still in contact**

******r**** at 228 T/m**

- r max < 160 MPa with dummy cable

- r = 120 m

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

##  = 110 mm - Conclusions

**	****	****	****	****IT CAN BE DONE!!!**
**SS collars + Outer shell support + Yoke gap closing during cooldown**
**Stresses < 150 MPa in every condition**
- Only exception is the midplane turn of the outermost layer that could be replaced by a dummy turn
**Gap Control Spacer will assure proper gap dimension at room temperature**
- CERN demonstrated they work well
**It’s a more rigid structure than with open gap**
- Gives the minimum coil displacement (field quality)
- Avoids over pre-stress of the coil
**The outer shell can be made of Al (< 30 mm) or SS (< 15 mm) **

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## 90 mm – “bladder & key” tech.

- By Shlomo Caspi

**Main features:**
**All pre-stress and support by Al outer shell**
**Assembly using bladders and keys**

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## “bladder & key” tech.

- By Shlomo Caspi

**Advantages (demonstrated with flat coils):**
**No loss of pre-stress**
**Simple assembly with good control of prestress**
**Outer shell may be re-used **
**Open questions****:**
**Effectiveness on shell-type quad**
**He vessel**

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## “Octagonal collars” concept

_***“***__***Octagonal collars” concept***_

**Main features:**
**octagonal shape of collars**
**collar/yoke interface is stable during cool-down (no angle change) **
**this should reduce the coil stress concentration.**
**alternately split yoke laminations **
**will support the coil assembly in two directions.**
**gaps between yoke lamination are closed during cool-down and some prestress is created by aluminum clamps and stainless steel skin to keep it closed under Lorentz forces.**

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## Conclusions

**Several designs have been studied, some of them are under further development, some new concepts and technologies will be studied.**
**	****Now we can say that:**
**90-mm**** aperture quad works with:**
**Stand-alone ss collars (with pole piece)**
**Outer shell (Al) support using bladders and keys**
**110-mm**** aperture quad works with:**
**SS ring-collars + outer shell support (Al or SS) on midplanes**

- By D.C.

- By S.C.

- By G.A.

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004

## Next steps

**First short models will have 90-mm aperture**
**Two mechanical designs will be tested:**
**Al outer shell with bladder & key, w/o collars (TQ4L1)**
**SS collars with and w/o additional support on midplanes (TQ2L1)**
- 90-mm aperture quad at G250 T/m could be used to simulate forces generated in larger aperture quads
**	****These tests are going to show the **_**advantages**_** and **_**limits**_** of each concept. The results will be the base for the design of the final prototype (concept and aperture). **
**Meanwhile we will continue to explore ****alternative concepts**** (as the “octagonal-collars”) and ****new technologies**** (as impregnated collars) in order to verify the possible advantages **

- Studies of single aperture IR quad mechanics - G.Ambrosio

- LAPAC - Jun 17-18, 2004