# Presentation: 124576

## Super-Ferric Injector in the SPS Tunnel

***- Motivation***
***- Magnet choice for the SF-SPS***
***- The SF-SPS accelerator arrangement***
***- Summary***

- _Super-Ferric Injector in the SPS Tunnel_

## Motivation

-     Replace current SPS accelerator with a machine that will enable to:
-            (1) Inject/stack two proton beams in the LHC (or in the LER, a
-                 possible pre-injector for the DLHC)
-            (2) Cycle two proton beams at 0.5 Hz (2 sec cycle) for the neutrino
-                 physics and other FT experiments

- Current CERN accelerator complex

- LER injector in LHC tunnel

## New SPS Magnet Considerations

-        As an injector to the LHC the SPS magnets must have a very high quality
- B-field to preserve good beam emittance at injection to LHC, necessary e.g. to
- minimize beam losses and facilitate good LHC performance.
-       The magnetic field in the gap is affected by both the conductor and the core.
- Maintaining a high quality B-field in the magnet gap during a fast ramping or
- cycling operation is a very difficult task due to significant AC power losses
- caused by eddy currents and magnetization with conductor embedded in the
- magnetic flux.
-       For the conductor dominated magnetic design, however, the required current
- in the coil is minimized by using multiple windings. Therefore, most of the fast cycling
- magnets use this option, but significant difficulties are encountered in the operation
- of such magnets due to AC losses.
-     To minimize the effect of the AC losses we propose to consider for the new SPS
-     a CORE dominated magnetic design in a super-ferric regime, hence SF-SPS.

## SF-SPS Magnet Consideration, part 2

- We propose a “frame” type core due to:
-                          -  high-quality B-field in the magnet gap
-                          -  minimized conductor effect on the B-field in the gap
-                          -  minimized physical size, and thus the magnet cost

-  This magnetic design is for a 2 Tesla
-  field in a 40 mm gap, with a single
-  conductor winding of 87 kA current,
-  and a laminated (1mm) Fe3%Si core.
-  Very little of magnetic flux crosses
-  conductor.

## Conductor Considerations

- Observation:
-    - For the current of ~100 kA a superconductor cable must be used
-    - About 300 strands of NbTi, or HTS can carry 100 kA current at 5 K
- Here are some possible SF-SPS conductor arrangements:

## Crudely Estimated Conductor AC Losses  

| Cable
type |   dB/dT

  [T/s] |   B max

   [T] | Power loss

 [W/m] |   2 T cycle time

    [s] |   4 T    cycle  time 

   [s]
      |   2 T cycle power loss per ring
  [kW] |   4 T cycle power loss per ring
 [kW] |
| --- | --- | --- | --- | --- | --- | --- | --- |
| NbTi single winding | 
     2 | 
    2 | 
    1 | 
    2 |  
   n.a. | 
    7 | 
  n.a. |
| HTS-344S single winding | 
    2 | 
    2 | 
   0.1 | 
    2 | 
   n.a. | 
   0.7 | 
  n.a. |
| NbTi (GSI) multiplewinding | 
    1 | 
    4 | 
     3 | 
    4 | 
    8 | 
   21 | 
  21 |

- The NbTi and HTS-344S single cable power losses are estimated.
- The NbTi multiple winding of GSI cable losses are measured.

- The required cooling power for the SPS single ring based on the GSI-type magnets
- is equal in size to the one LHC cryo-plant.

##  Possible Cycling Times with  SF-SPS

- As a result of low cooling power demand in SF-SPS magnet we assume two rings (DSF-SPS)
- will accelerate interchangeably beams from PS2 leading to the following cycling  times:
-     (1) Collider operation; T cycle ~ 14 sec / beam including ~10 sec
-          stacking time (current SPS super-cycle / beam ~ 22 sec)
-     (2) Fixed Target operations; T cycle ~ 2 sec
-          (current minimum cycle / beam ~ 8 sec)

## Proposed DSF-SPS Accelerator Arrangement

- DSF-SPS arrangement:
- Single transmission-line conductor, PS and CL per ring
- Both rings will share interchangeably a common RF power

## DSF-SPS Power Supply and Current Leads

- DSF-SPS Power supply design (S. Hays) will be based on the MI power supply, with
- exception that it will be twice the MI PS power.
- The current leads (Y. Huang) will use the HTS cable with increasing number of
- strands as the cold end of the copper leads is approached.

## DSF-SPS Magnets

- Magnet list is based on a preliminary lattice design by J. Johnstone.
- The arc magnets are combined function dipoles. Cell length = 63.99 m
- Phase / cell = 92.50  , β max = 96.4 m,  η max = 3.81 m

| Cell type | Magnet type | L magnet [m] |       B [T] |     B’ [T/m] |    Number |
| --- | --- | --- | --- | --- | --- |
| Arc sections |       GF/GD
         QF
        QTF |      7.165
     0.660
     0.339 |       1.9 |       +/- 4.7
   +/- 70.00
   +/- 70.00 |      744
         6
         6 |
| Straight sections |     QF/QD |      0.660 |  |    +/- 70.00 |        48 |
| 
Total |  |  |  |  | 
     804 |

## DSF-SPS Cost Estimate

- This crude cost estimate is based on the cost studies for
- the VLHC with an updated material cost to the 2006 $.

| DSF-SPS subsystem |          [$M] |
| --- | --- |
| Arc magnets*) |          200 |
| Correctors |            10 |
| RF system |            40 |
| Beam pipe vacuum system |            20
 |
| Cryogenic plant |            20 |
| Magnet R&D |              5 |
| Prototyping |              5 |
| Total |          300 |

## Summary

- -  The DSF-SPS accelerator will provide high quality beams for
-     the injection to the LHC shortening the LHC cycle in the same
-     time
- and
- -   It will allow for a 4-fold increase of target power for the neutrino experiments.