CLIC potential baseline changes CTC items

CLIC potential baseline changes CTC items

H. Schmickler, G. Riddone - 11.12.2009

2

Item Baseline Alternative

Machine protection Next pulse permit: 18 ms + 2 ms protection for slow lossesCollimators/masks for fast losses

?

Tunnel cross-section Tunnel diameter (4.5 m) mainly imposed by transverse ventilation

Longitudinal ventilation

Bigger tunnel

BDS L* 3.5 m 6-8 m

MB + DB girder 2 individual girders Common girder

MB + DB girder 2m long girders Longer girders

3


Damping ring wigglers:

superconducting Normal conducting; at least for 500 GeV parameters

Drive beam RF power generation

33 MW (peak power) klystrons

10 – 15 MW (peak power) klystrons

Drive beam phase and amplitude control

Baseline under workBy BDWG

As soon as baseline available, will need follow-up through CTC.

DB, MB phase alignment RT feedback

Baseline under work By BDWG

Turnaround magnets

Normal-conducting magnets

Permanent magnets + 10 % trims

Motivated by stability requirements? For phase stability; also power consumption

4


Corrector dipoles (main beam)

No corrector dipoles Common actuators for stabilization and BBF

Re-introduce corrector dipoles

Stabilization system(main beam)

Electromechanical sensors and actuators in RT feedback

Common MIMO system with BBF

Pre-alignment system

Conventional WPS/HDL sensorsSnake system with articulation point andlinear actuators

Low-cost sensors Cam system moversLaser system

Beam Instrumentation (MB)

4000 cavity BPMs with one horizontal/one vertical read-out

4000 cavity BPMs with two horizontal/ two vertical read-outs

Beam instrumentation (DB)

One BPM per Q Fewer BPM

Conclusiontaken from M.Jonker; last Friday (56 pages)

The base line machine protection provides an adequate framework for protection against fast and slow failures.

The large amount of time available between pulses allows an exhaustive post pulse analysis to authorize the next pulse.

The challenging issues: mask and spoilers to– Intercept a single main bunch up to a full main train

– intercept a “derailed” decelerator train.

More info is needed to estimate consequences of RF failures.

Kickers reliability to be looked into.

L*=3,5m and L*=6(8)m• Complicated optimization:

Shorter L*= higher luminosity, easier insertion tuningLonger L* = lower luminosity, easier to achieve technical solution for vibration stability

• Lots of progress in the past months on:- design of FF magnets- vibration measurements- studies on possibilities of active stabilization- physics detector size- knowledge on boundary conditions from experiments

• Still it seems not possible to decide for a layout with convincing feasibility for the CDR now: Conclusion: Follow studies and designs for both optionsL*=3,5m and L*=6(8)m; Can we at least decide 6 or 8 or 6,42?

How does the cost of a klystrons scale with peak power?

• Probably: cost per klystron proportional to (peak power)1/2 (*)

• At a level of around 15 MW peak, the slope will become steeper due to increased system complexity.

• This leads to the following model:

• Blue: present state of the art • Red: assuming a major investment into the development of a dedicated 30

MW tube(*) rule of thumb given by T. Habermann/CPI. Rees/LANL estimates P0.2 for 0.5 to 5 MW tubes.

807/Apr/2009 CTC#13: Erk Jensen - RF system for the Drive Beam Linac

Erk Jensen

Cost per MW

• Using the above model, here’s the klystron cost per MW (peak)

• Blue: present state of the art • Red: assuming a major investment into the development of a

dedicated 30 MW tube


Tube lifetime

• In spite of its price, a klystron is a consumable! • A klystron has a finite lifetime; this will also depend on its

internal complexity (and on the peak power!).• The lifetime will depend on many parameters, primarily the

current density, but here’s one estimate ...


What about an MBK?: is the tube dead if one of n beams fails? If the design is good, the n beams would fail at around the same time ...

Cost for 100,000 operating hours and MW

• Even if this model may be wrong, there will be a cost per MW and per operating hour: With the above model, this becomes:

• Blue: present state of the art • Red: assuming a major investment into the development of a

dedicated 30 MW tube1107/Apr/2009 CTC#13: Erk Jensen - RF system for the Drive Beam Linac

C L I CC L I C

17th November 2009CTC meeting L. Rinolfi

Pre-Injector e- Linac

MKS 01 MKS 02 MKS 03

2 GHz

40 MW

2 GHz

DC Gun

PB2 B1A1 A2 A3 A4

SLED

40 MW

2 GHz

SLED

50 Hz50 Hz50 Hz

40 MW

PB1

20 MeV200 MeV

Accelerating cavities:

• Number of cavities: N = 4• Length: L = 3 m• Aperture radius: r = 20 mm• Energy Gain: E = 45 MeV• Accelerat. gradient: Ez = 15 MV/m• Frequency: f = 2 GHz

Louis Rinolfi

C L I CC L I C

17th November 2009CTC meeting L. Rinolfi

• Erks optimization of the unit klystron power isbased on maintenance and reliability questions combined with lowest price/MW.

• The optimization has been done for the DB linac, since there we have the largest klystron installation.

•The base line change for the klystron power demands a reoptimization of the linac structures (#cells).This is almost done; base line change should be made.

• The same logic should be applied for all other linacs (injectors, bunch compressors…). This also needs a (re)design of the connected RF-structures.

Background (1/2)

• 4000 MB quads, need about 80 correctors close to quads for beam-based feedback (BBF);

• Pre-choice of 80 locations impossible? equip all 4000 quads with correctors

• Frequency range covered by BBF: sub-Hz to ~1 Hz• In order to

- have some feedback gain at f_cl =1 Hz (f_cl = f_s/gain)- to average over several BPM readings the BBF will run at a sampling frequency f_s=50 Hz;

i.e. the corrections are applied every pulse:requested settling time of corrections is 5 ms( in-between 2 beam pulses )

Background (2/2)

• Technical implementation in 2008:- additional windings onto quad jokes in order to produce “a sort of dipole correction field”

• Pre-Choice of non-laminated MB quads for stabilization and mechanical engineering (late 2008)excludes correction coil (bandwidth problem)

• Present design approach: Extend dynamic range of stabilization actuators by 100 ! and make BBF corrections by displacing the MB quads.Fullscale = +- 5 um compared to +- 50nm

Problems with present implementation

• Actuator dynamics, in particular for the (long) heavy magnets

• Absolute position of quad in beam reference frame not know (Hexapod design with sub-nm position readout in each leg)

• BPMs (50 nm required resolution) will move with quad.Needs sophisticated bookkeeping of past displacements.BPM close to “zero” and for longer elongations non-linear (monopole and quadrupole mode signals)

• Machine protection: non-energized position of quad (vertical) is max.down, not middle; might need interlocks.

Implementation• Required corrector strength (Bdl):

200 T/m *10 um * 2m (@ 1.5 TeV) = 4 mT * m = 0,4 T * 1 cm - very week magnet

assumed strength: scales with length of Q corrector@ Q1: 0,1 mTm

• 1 cm long 0.1 - 0.4 T magnets• - end-field problems?

- interference with quad field?- will create synchrotron radiation?(200 times higher bending radius)

MB-Q

Prealignment

Stabilization

2 x 2000 MB-Qs

4 types (lengths)

All MB-Qs need stabilization equipment:

Postion sensors (v- sensors+ integration ora-sensors + double integration)

Piezoelectrical actuators (presently hexapod design)

WPS and HLS plus overlapping wires as reference

Linear motors as actuators

Controller – topology?

Sensors and Actuators?

BPM on each Quaddipole corrector on each quad

Prealignment without beamWith beam:

Beam based feedback (all BPMs + about 80 actuators)

Quad Stabilization (sensors + actuators on each Quad)

• Pre-alignment:- overlapping stretched wires, WPS, HLS as baseline for CDR- linear actuators- continuing studies on laser systems (start with IP)and on camshaft movers- controller: local or central: decision not needed

• Beam based feedback:- based on MB BPMs: open question for CDR:- online dispersion measurements by in-pulse energy variation or by pulse to pulse variation?- actuators: small dipole correctors- controller: First design needed for CDR

• MB-Q stabilization- for CDR: sensors and actuators, independent (local) controllersinteresting alternative to be studied: sensors as before, but common controller with BBF and small dipole correctors as actuators (“move the beam within a vibrating quadrupole rather than stabilizing the magnet”)

HFSS EigenMode Calculation

(II) Bunch trajectories (I) Matched Impedance, P_coax

HFSS Data:

W - Stored EnergyP_coax - Exited RF PowerEz - E-field along bunch

pathgsym - Symmetry coefficient

Cavity BPM spectrum calculation

00 0*

*2*

L j t

scaleHFSS sym

Ez e dzq qk

q g W

Scale Factor:

Output Power:

211 )(*)(_)( scaleTM krcoaxPrP

r

e- Estimated Sensitivity (q0 = 1nQ):

r

OhmrPS TM ][50*)(11 V/nQ/mm

Choice not obvious: tradeoff between number of BPMs and precision; availibility, cost versus precision, risk….

Taken from E.Adli’s presentation

July 2009A. Lunin, Fermilab

Port 1Port 2

Port 4Port 3

a)

b)

c)

BPM Mechanical Tolerances

There is no visual advantage of particular scheme of coaxial layout (a, b, c)

The most sensitive to mechanical errors part of the BPM is a coupling slot.

The required mechanical tolerances of a cavity with coupling slots:

Mechanical

Tolerances1,2

Cross

Coupling

-40 dB

Cross

Coupling

-30 dB

Cross

Coupling

-20 dB

Slot Rotation, [deg] < 0.05 < 0.2 < 0.6

Slot Shift, [μm] < 5 < 15 < 40

Other, [μm] < 50 < 50 < 50

Max Dynamic

Range, [μm]

100 25 10

1 - In-phase signals reflection (worse case) is taken into account.2 – The reflection from LLRF part is assumed less than -20 dB.

Summary BPMs MB: At each MB-Q Cavity BPMs (FNAL Design)

with integrated reference cavity for intensity information.Small study needed for extra cost of double readout vs redundancy and on-line calibration benefits.

DB: Large number: at each DB quadtechnical choice of DB BPM: BI group + collaborators in 2010- compromise between cost reduction, extra effort for better alignment in case of reduction of BPMs etc not before CDR.

Color codes used

= could be decided today

= needs some work, decision before CDR writeup ..i.e. before summer 2010

= interesting alternative, decision not before CDR

33

Item Baseline Comment Follow-up

Machine protection Next pulse permit: 18 ms + 2 ms protection for slow lossesCollimators/masks for fast losses

Tunnel cross-section Tunnel diameter (4.5 m) mainly imposed by transverse ventilation

Overall coherent machine layout (BDS, RTML….) to be defined before CDR

BDS L* 3.5 m 6 m

MB + DB girder 2 individual girders Common girder

MB + DB girder 2m long girders Longer girders

Describe both options in CDR

34

Item Baseline Follow-up

Damping ring wigglers:

superconducting Normal conducting; at least for 500 GeV parameters

Drive beam RF power generation

33 MW (peak power) klystrons

10 – 15 MW (peak power) klystrons

Drive beam phase and amplitude control

Baseline under workBy BDWG

As soon as baseline available, will need follow-up through CTC.

DB, MB phase alignment RT feedback

Baseline under work By BDWG

Turnaround magnets

Normal-conducting magnets

Permanent magnets + 10 % trims

Motivated by stability requirements? For phase stability; also power consumption

35

Item Baseline Alternative Follow-up

Corrector dipoles (main beam)

No corrector dipoles Common actuators for stabilization and BBF

Re-introduce corrector dipoles

Stabilization system(main beam)

Electromechanical sensors and actuators in RT feedback

Common MIMO system with BBF

Pre-alignment system

Conventional WPS/HDL sensorsSnake system with articulation point andlinear actuators

Low-cost sensors Cam system moversLaser system

Beam Instrumentation (MB)

4000 cavity BPMs with one horizontal/one vertical read-out

4000 cavity BPMs with two horizontal/ two vertical read-outs

Beam instrumentation (DB)

One BPM per Q Fewer BPM

CLIC potential baseline changes CTC items

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