plan for the rest of commissioning

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15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Brief summary of

run #10 (23
-
25 September)

and

plan for the rest of commissioning

Shinji Machida

o
n behalf of the beam commissioning team

ASTeC
/STFC/RAL

27 September 2010

1

Aims


Understand
rf

system


Phase with respect to beam


Vector sum voltage


Time of flight with +2 mm shifted lattice.


Closed orbit measurement and its correction.


Understand “improvement” by QD27.



2

rf

system (1)

vector sum


When all cavities have the “same” phase


Observed
syn

period is 20 turns instead of 14.


A beam sees only a half of
rf

voltage, 0.5 MV.


When 10 cavities have the “same” phase and
9 cavities have the opposite phase


Observed
syn

period is 43 turns instead of 61.


A beam sees twice as much voltage, 0.11 MV.


Individual phase has to be set by using a
beam.

3

rf

system (2)

phase with respect to a beam


Global phase moves with respect to a beam
once we use “sweep
rf
” button.


Necessary after trip.


Make it hard to determine individual cavity phase
by single cavity excitation.

4

rf

system (3)

measurement of individual phase


With all cavity turned on with 10 acc. and 9
dec
. phase, change phase of only one cavity.


Can find zero crossing of the cavity.


Difficult to distinguish rising or falling edge.


Change individual cavity phase and monitor
rf

voltage of the cavity (Yuri).


Beam loading tells the phase of crest.


Although it is tedious to find crest phase of the all
cavities, it is the only promising way to determine
individual
rf

phase.


5

Lattice


With all the
quadrupole

+2 mm shifted
outside, time of flight increased as expected.


There is enough aperture with 20.5
MeV/c

equivalent momentum and the nominal
QD/QF ratio.


Shifted
quadrupole

lattice helps to match
rf

frequency range (+1.5,
-
4 MHz) to
ToF
.


Issue is whether we still have enough move for
COD correction. QD has +/
-

2.6 mm move only.

6

COD measurement and correction (1)

method


Total 12 BPM cables are available.


12 H or V signals at one time.


Switch off the machine 3 times to measure the
whole 42 cell BPM for horizontal COD
measurement and another 3 switch off for
vertical.


Seems the only way at least before shutdown.

7

COD measurement and correction (2)

preliminary result


Both horizontal and vertical COD at BPM
between QD and QF are measured.


One set with QD27 with the same current as
the rest. Another set with QD27 with 10%
more current.


Preliminary results show COD of more than
+/
-

6 mm in horizontal.

8

COD measurement and correction (3)

correction


Attempt to correct horizontal COD.


David analyzing the data.

9

Next step (1)

main issues


Toward the demonstration of acceleration,
two major (may be more) problems to be
fixed.


Set individual cavity phase to maximum vector
sum.


Correct closed orbit distortion.


Fix lattice for the demonstration.


14.5
MeV/c

is the minimum momentum?


Need
quadrupole

shift for the matching of
ToF
?


10

Beam time (1)


Run #1:


20
-
23 June 2010


Run #2:


12
-
15 July 2010


Run #3:


27
-
29 July 2010


Run #4:


3
-
6 August 2010




end of 4 sector


Run #5:


13
-
15 August 2010



full ring


Run #6:


18
-
24 August 2010



rf

commissioning


Run #7:


30 August


2 September 2010

rf

available


Run #8:


7
-
10 September


Run #9:


15
-
18 September


Run #10:

24
-
26 September


Run #11:

2
-
3 October


Run #12:

10
-
13 October

11

Beam time (2)


Run #11:

Saturday 2


Sunday 3 October


Both Shift 2 and 3


Mark’s data taking in tomography section on 2 October.


rf

on 2 October, but no
rf

on 3 October.


May have additional
shift(s
) on 4 October.


Run #12:

Sunday 10


Wednesday 13 October


Shift 2 and 3 on 10 October.


Shift 3 only from 11 to 13 October, but shift 2 may become available.


May have additional
shift(s
) on 14 October.


6 to 8 days before shutdown in the middle of October.

12

Next step (2)

lattice for the demonstration


Probably not a good idea to shift
quadrupole

to make injection easier and to match
ToF
.


At least +/
-

1 mm translation should be reserved
for COD correction.


1.301 GHz
rf

synchronizes with revolution
frequency of 18.5
MeV/c

lattice with
QD/QF=205/196 A.


Is it possible to inject 14.5
MeV/c

equiv. or
lower beam without
quadrupole

translation?


Need to lower QF current?



13

Next step (3)

individual phase measurement


Measure individual cavity phase at the next
shift with rf.


Beam loading measurement seems to work.


May need one or two shifts to measure the
phase of 19 cavities and measure vector sum.



Main subject of 2 October.



14

Next step (4)

COD correction


Analyze measured COD and calculate
individual
quadrupole

shift for correction.


May need several correction algorism.


Measurement of response matrix if necessary.



Main subject of 3 October.


15

Next step (5)

plan for the final week


With 18.5
MeV/c

equiv. beam and
QD/QF=205/196 A lattice,


Correct COD.


Scan global
rf

phase for capturing in a bucket and
deceleration in serpentine channel.


Measure tune
vs

turn for plausible case.



With 14.5
MeV/c

(or less) equiv. beam,


Measure and correct COD


Scan global
rf

phase for acceleration in serpentine
channel.


16