Tools in CTF3Simona Bettoni

for the CTF3 operation team

2

Outline

→ The modeling:

→ Quad scans

→ Online model

→ The automatization of the measurements in CTF3:

→ Reading and writing on the machine

→ The measurements:

→ kick measurements

→ Dispersion measurements

→ Tune measurements

→ The tools:

→ Orbit correction in the ring

→ Orbit correction in the LINAC (see E. Adli talk)

3

Online MAD-X model of the machine

The currents in the machine are read and

the K values are calculated

The currents of the quads can be read and directly sent to the machine

Energy profile and starting optical

parameters (LINAC) are used

Several matchings can be easily integrated

4

Online MAD-X model of the machine: energy profile

→ The energy profile is determined from the loading in the klystrons

→ Excel spreadsheet used

Input power in a klystron

and beam current

Extracted power

Beam acceleration

Beam energy variation in each

structure

5

Online MAD-X model of the machine: initial conditions

→ Six monitors are installed in the machine to measure the twiss parameters and the emittances

MTV locations

Reading and writing on the machine

function [ quads, dipols, hcors, vcors, mons ] = cr()

→ For each part of the machine a Matlab function defines the structure of the line or the ring (kind of

equipment and name in the MAD model, status of the device)

Magnets Beam position monitors

Part of the machine

→ Function to automatically read and write the currents in the magnets

function writedevices(devdescr,values)

function readvalues = readdevices(devdescr)

6

→ Function to read the orbit

function [hmean, vmean, currmean] = readorbit (devdescr, navg, nturn)

Positions and beam current Device description and # averaging and turns (ring)

7

Kick measurements

→ A reference orbit and the beam current along the line (ring) are measured

→ The current in a corrector is changed

→ The new orbit and the current in each beam position monitor are saved

→ The orbit variation is compared to the MAD model prediction

8

CLEX

CR

TL1

DL

TL2

ACCELERATING STRUCTURES

Dispersion measurements: local

→ The contribution to the dispersion of each part of the machine is isolated and compared to the model

predictions assuming 0 incoming dispersion

→ A reference orbit along the line (ring) is measured

→ The magnets in the line (ring) are scaled (typically of

fraction of % or %)

→ From the orbit variation the dispersion is calculated

LARGE FLUCTUATIONS

9

Dispersion: online and global measurement

Frascati chicane

→ A reference orbit of one shot saved along the machine

→ The orbit variation in a not free and well known dispersion (Frascati chicane) is used to compute the shot

to shot energy deviation: from Dx (Dy) to Dp/p

→ Known the energy jittering, measuring the orbit deviation along the entire machine, the dispersion is

computed: from Dp/p to Dx (Dy)

10

Dispersion measurements: energy step

→ An energy variation along the pulse in the last klystron of the LINAC is introduced

→ The beam position difference between the different parts of the pulse in the BPM is used to determine

the dispersion

11

Tune measurements

→ The measurement:

→ Tune determined from the Fourier transform of

the H (V) signal in a BPM (scope signal)

→ Compromise between oscillation amplitude

and number of turns (typically about 200)

→ Scan varying the current in a quads family

→ The model comparison:

→ Scan of the tunes as a function of the current in a quads

family

→ Automatic scan over the energy range

f MAIN

fQ

12

Orbit correction: the algorithm

IREFBPM IRMxx minRM: response matrixXBPM: transverse beam displacement at BPMxREF: reference orbit at BPMI: currents in the correctors

*Closed orbit correction using singular value decomposition of the response matrix, Y. Chung, G. Decker, K. Evans Jr., PAC 93 proceeding.

* SVD decomposition

BPMREF xxx

xRI )(~ TUWVR )(

~)(

~

IIRMx min

where

Singularity rejection parameter (eps)

0

1

Normally most accurate orbit correction, BUT large current values can be obtained

No orbit correction ( null matrix))(~ R

Orbit correction: the algorithm improvement

Best eps value iteratively determined: → Tolerance on the maximum allowed beam displacement and maximum value of the currents in

the correctorseps_start = 1 n_max_step = 10000; fact = 1; for i = 1:n_max_step

if i == 1 eps(i) = eps_start*fact; else eps(i) = eps(i-1)*fact; end [theta_s,thetap_s,corr_s,final_s,idec_s] = correction_1_mod(eps(i),RM',x_BP'); Curr_tot_s(i,:) = start_corr'+theta_s; Curr_tot_max(i) = max(abs(start_corr'+theta_s));

if abs(Curr_tot_max(i)) > max_I_corrs_tol fact = 1.1; else x_max_exp = max(abs(x_BP+RM'*theta_s));

if x_max_exp < tol break else end fact = 0.9; end end Curr_tot = Curr_tot_s(end,:);

Starting inputs

Eps value

Check and new eps value

13

14

Orbit correction: the response matrix

Orbit closure:

→ The response matrix is built using both the first and the second turn orbits

Kicks in the correctors: → The value of the kick in each corrector is determined according to the maximum tolerated losses

in the last read BPM/BPI

Turn 1Turn 2

145-S 200 242 252 292 345 408 452

155 195 208 248 275 305 395 405

Correctors

BPM/BPI

QF

G01

20

QD

G01

40

QD

F01

60

QF

F01

90

QFJ0215QDJ0230

QFJ0245

QFJ0415

QDJ0430

QFJ0445

QDH0340

QFJ0320

QDH0360

QFJ0380

QFJ0455

QDJ0470

QFJ0485

QFJ0255

QDJ0270

QFJ0285

BHF0205BHF0995

BHF0905

BHF0795

BHF0750

BHF0950BHF0250

BHF0295

BHF0405

BHF0450

HD

S01

50

WHA0350

XLB0210

XHB0220

XVB0240

XVB0260

XHB0280

XLB0290

XLB0410

XHB0420

XVB0440

QF

G05

80

QD

G05

60

QD

F05

40

QF

F05

10

CC

.SH

C 0

120

CC

.SH

D 0

110

KH

B 0

550

QF

F10

10

QD

F10

40

QD

G10

60

QF

G10

80

HD

S10

50

QF

F06

90

QD

F06

60

QD

G06

40

QF

G06

20

QFJ0715

QDJ0730QFJ0745

XLB0490

XHB0480

XVB0460

XLB0710

XHB0720XVB0740

XVB0760

XHB0780

XLB0790

QFJ0755

QDJ0770

QFJ0785

QDH0840

QFJ0820

QDH0860

QFJ0880

XLB0910

XHB0920

XVB0940

QFJ0915

QDJ0930

QFJ0945

QFJ0955

QDJ0970

QFJ0985

XLB0990XHB0980

XVB0960 CT

.SH

C 0

780

CT

.SH

D 0

790

BHF0495BHF0705

DHF/DVF 0252

DHF/DVF 0292

DHF/DVF 0345

DHF/DVF 0408

DHF/DVF 0242

DH

F/D

VF

0200

DH

F/D

VF

01

45

DH

F/D

VF

10

00

DHF/DVF 0452

DHF/DVF 0492

DH

F/D

VF

01

47

Kick at corrector 252

15

Orbit correction: the results

Inputs:

→ Tolerated maximum x-displacement = 4 mm

→ Maximum current in the correctors = 10 A

→ Maximum allowed losses = 10%

Before the correction

After the correction

16

Orbit correction: the energy jittering

→ Tolerance on the orbit correction limited by the incoming orbit jittering

→ Possible cures:→ Increase the number of averaging (time consuming)

→ Subtract the orbit jittering due to dispersion pattern (to be tested next week)

17

Orbit correction: model-based correction

Use the model response matrix to correct the orbit at least for the first iteration:

→ Quicker (response matrix measurement takes about 20 minutes)

→ Immediately scaled for the energy

QF

G01

20

QD

G01

40

QD

F01

60

QF

F01

90

QFJ0215QDJ0230

QFJ0245

QFJ0415

QDJ0430

QFJ0445

QDH0340

QFJ0320

QDH0360

QFJ0380

QFJ0455

QDJ0470

QFJ0485

QFJ0255

QDJ0270

QFJ0285

BHF0205BHF0995

BHF0905

BHF0795

BHF0750

BHF0950BHF0250

BHF0295

BHF0405

BHF0450

HD

S01

50

WHA0350

XLB0210

XHB0220

XVB0240

XVB0260

XHB0280

XLB0290

XLB0410

XHB0420

XVB0440

QF

G05

80

QD

G05

60

QD

F05

40

QF

F05

10

CC

.SH

C 0

120

CC

.SH

D 0

110

KH

B 0

550

QF

F10

10

QD

F10

40

QD

G10

60

QF

G10

80

HD

S10

50

QF

F06

90

QD

F06

60

QD

G06

40

QF

G06

20

QFJ0715

QDJ0730QFJ0745

XLB0490

XHB0480

XVB0460

XLB0710

XHB0720XVB0740

XVB0760

XHB0780

XLB0790

QFJ0755

QDJ0770

QFJ0785

QDH0840

QFJ0820

QDH0860

QFJ0880

XLB0910

XHB0920

XVB0940

QFJ0915

QDJ0930

QFJ0945

QFJ0955

QDJ0970

QFJ0985

XLB0990XHB0980

XVB0960 CT

.SH

C 0

780

CT

.SH

D 0

790

BHF0495BHF0705

DHF/DVF 0252

DHF/DVF 0292

DHF/DVF 0345

DHF/DVF 0408

DHF/DVF 0242

DH

F/D

VF

0200

DH

F/D

VF

01

45

DH

F/D

VF

10

00

DHF/DVF 0452

DHF/DVF 0492

DH

F/D

VF

01

47

18

Conclusions

→ In CTF3 Matlab scripts have been developed to modify the machine settings and read the orbits in the machine. This allows to do automatically:→ Kick measurements

→ Dispersion measurements

→ Quad scans

→ Several tools have been developed to determine the optics model and to operate the machine:

→ Online model

→ Tune measurements

→ Orbit correction

→ Future developments:→ Better study of the dependence of the measurements (kick and dispersion) on the energy jittering→ Tune measurement automatization→ Integration of the Matlab tools in the control system (more user-friendly)

19

Extra slides

20

Orbit correction: the results (vertical)

Before the correction

After the correction

Inputs:→ Tolerated maximum y-displacement = 1.5 mm→ Maximum current in the correctors = 10 A→ Maximum allowed losses = 10%