8th esls rf workshop daresbury 29-30 september 2004 super-3hc - m.svandrlik 1 g.penco, m.svandrlik...

18th ESLS RF WorkshopDaresbury 29-30 September 2004

SUPER-3HC - M.Svandrlik

G.Penco, G.Penco, M.SvandrlikM.Svandrlik

• Operation

• Uptime

• Maintenance

• Performance vs filling

• Conclusions

SUPER-3HC at ELETTRA UpdateSUPER-3HC at ELETTRA Update



• 3HC is routinely in operation during user’s shifts.

• Lifetime depends on ultimate vacuum conditioning and filling pattern, highest value we can obtain is 27 hrs(320 mA; 2.0 GeV)

• Filling pattern set to 96%

• During refill and energy ramping 3HC set at +94 kHz (from 3rd harmonic) - Transverse Feedbacks ON

• Once beam is at 2.0 Gev 3HC is activated by tuning it at +64 kHz

• Longitudinal Coupled Bunch Instabilities are cured by 3HC, Transverse Instabilities are cured by Feedbacks.

OperationOperation/Uptime/Maintenance/Performance vs Filling/Uptime/Maintenance/Performance vs Filling



• The increase in Beam Lifetime obtained when 3HC is active, allows us to refill ELETTRA every 36 hrs instead of 24 hrs, as it used to be in the past.

OperationOperation/Uptime/Maintenance/Performance vs Filling/Uptime/Maintenance/Performance vs Filling

3HC tuned:only 3 refills in 5 days operation

How it wasbefore 3HC



0,0 0,0 0,0

15,8

0,0 0,6 0,00

5

10

15

20

25

30

RUN 85AUG - SEP 03

RUN 86SEP - OCT 03

RUN 87NOV - DEC 03

RUN 88JAN - FEB 04

RUN 89MAR - APR 04

RUN 90APR - MAG 04

RUN 91JUN - JUL 04

Users' downtime caused by 3HC, in hours

• General uptime of the system is good. Since September 2003 only one event caused significant User’s downtime, on Saturday, 31/01/2004.

Operation/Operation/UptimeUptime/Maintenance/Performance vs Filling/Maintenance/Performance vs Filling



• The event on 31/01/04 was related to a failure of a rough pumping unit of the valve-box insulation vacuum. This was a temporary installation, replaced during the next shutdown with a fail-safe one.

• The uptime statistics does not include systems stops due to electrical power interruptions, mostly caused by thunderstorms in the surroundings. In this case most machine systems are stopped and the restart time of the cryogenic plant is hidden in the general restart of the systems. For this reason the idea of connecting 3HC to a new UPS has not yet been implemented (also financial reasons).

• We still do not have a He recovery system, the experience made so far shows that we can survive without it, not affecting the uptime of the system.

Operation/Operation/UptimeUptime/Maintenance/Performance vs Filling/Maintenance/Performance vs Filling



• Several important maintenance interventions have been successfully performed in the last 12 months.

• In November 2003 the leaky gate valve between 3HC and the superconducting wiggler was substituted.

Operation/Uptime/Operation/Uptime/MaintenanceMaintenance/Performance vs Filling/Performance vs Filling

This required to break the cavity vacuum. A clean area was therefore created inside the storage ring tunnel. The replacement followed clean room procedures and was done by CEA and Elettra staff.The field performance of the cavity has not been affected by this intervention.



• In December 2003 the tuning system of cell 1 failed for the 2nd time (1st time in March). In January 2004 the tuning system was replaced with an upgraded version.

• The tuning system is under vacuum, at cold. The gear box was found to be blocked.

• Tests at Saclay showed that the reason could be a heating problem (from the motor).


• Even if the number of cycles after which this shows up is huge, we are limiting the movements of the system.

• No problem since January 04• CEA is studying a solution to

move the motor outside the cryomodule.



• During the January shutdown the cryogenic plant annual maintenance was performed.

• After this maintenance the nominal performance is back to the original, i.e. about 30-35 litres/hour at 13 bar of HP.

• In August 2004 the cryomodule has been warmed-up again in order to replace a coaxial cable which takes out the voltage signal of cell 2.

• In this occasion also the fundamental mode rejection of the dipolar HOM couplers has been improved. In fact on one of them some over-heating effects were observed when tuning the cell.




Operation/Uptime/Maintenance/Operation/Uptime/Maintenance/Performance vs FillingPerformance vs Filling

• ELETTRA used to operate with a partial filling of the bunch train: typically a 10% empty gap was present.

• As well known, with such a gap the passive third harmonic cavity induces a phase modulation over the bunch train.

• Several STREAK CAMERA experiments were performed for various fillings, measuring the effect on:

– Phase Shift

– Bunch lengthening

– Landau Damping

– Beam Lifetime

• As a result, a new optimum filling was set for operations.



Phase Shift along the train for different tuning

10

20

30

40

50

60

600 700 800 900 1000 1100 1200 1300 1400 1500Bunch position in the train (ps)

Re

lati

ve

Ph

as

e (

De

g)

1499,070 MHz

1499,060 MHz

1499,050 MHz

1499,025 MHz

1499,020 MHz

1499,015 MHz

Bunch length along the train for different tuning

30

40

50

60

70

80

90

700 900 1100 1300 1500Bunch position in the train (ps)

RM

S B

un

ch

Le

ng

th (

ps

)

1499,070 MHz

1499,060 MHz

1499,050 MHz

1499,025 MHz

1499,020 MHz

1499,015 MHz

Ibeam=315mA, Filling at 80%

Ibeam=315mA, Filling at 80%

80% Filling:80% Filling: Phase Shift/Bunch Length Phase Shift/Bunch Length/Landau/Lifetime/Landau/Lifetime



Phase Shift along the train for different tuning

10

15

20

25

30

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40

45

50

0 200 400 600 800

Bunch position in the train (ps)

Rel

ativ

e P

has

e (D

eg)

1499,050 MHz 1499,040 MHz

1499,030 MHz 1499,025 MHz

1499,020 MHz 1499,015 MHz

1499,014 MHzBunch length along the train for different tuning

20

40

60

80

100

120

140

160

180

200

0 200 400 600 800Bunch position in the train (ps)

RM

S B

un

ch

Le

ng

th (

ps

)

1499,050 MHz 1499,040 MHz 1499,030 MHz

1499,025 MHz 1499,020 MHz 1499,015 MHz

1499,014 MHz

Bunch overstretching

Ibeam=315mA, Uniform Filling

Ibeam=315mA, Uniform Filling

100% Filling:100% Filling: Phase Shift/Bunch Length Phase Shift/Bunch Length/Landau/Lifetime/Landau/Lifetime



f= +92 kHz f= +82 kHz f= +62 kHzf= +72 kHz

The Bunch Profile Averaged on the bunch train in the case of Uniform

Filling is shown below for different tuning positions of 3HC. The “nominal

tuning” of 3HC would be around +75 kHz. Beyond this postion the Bunch

begins to show an overstreched profile. Beam Lifetime increases until the

position of +62 kHz, which is the operating position. A few kHz beyond that,

lifetime starts to decay to a few hours; further the beam is lost.

100% Filling:100% Filling: Phase Shift/Phase Shift/Bunch LengthBunch Length/Landau/Lifetime/Landau/Lifetime



Phase Shift along the bunch train

0

5

10

15

20

25

30

35

40

45

1499.010 1499.015 1499.020 1499.025 1499.030 1499.035 1499.040 1499.045 1499.050 1499.055 1499.060 1499.065 1499.070

3HC Frequency (MHz)

Deg

Uniform FillingFilling at 98%Filling at 96%Filling at 90%Filling at 80%Filling at 70%

Various Fillings: Phase ShiftVarious Fillings: Phase Shift/Bunch Length/Landau/Lifetime/Bunch Length/Landau/Lifetime



Bunch length along the train

30

40

50

60

70

80

90

100

110

120

130

140

1499.010 1499.015 1499.020 1499.025 1499.030 1499.035 1499.040 1499.045 1499.050 1499.055 1499.060 1499.065 1499.070

3HC Frequency (MHz)

<> (ps)

Filling at 70%Filling at 80%Filling at 90%Filling at 96%

Filling at 98%Uniform Filling

Various Fillings: Various Fillings: Phase Shift/Phase Shift/Bunch LengthBunch Length/Landau/Lifetime/Landau/Lifetime



The Landau damping seems to be influenced by the different contribution of the increasing gap width and of the average bunch length, which is reduced as the gap increases.

Various Fillings: Various Fillings: Phase Shift/Bunch Length/Phase Shift/Bunch Length/LandauLandau/Lifetime/Lifetime

Scale isdifferent!



Uniform Filling90% Filling

f= +112 kHzf= +112 kHz

f= +92 kHzf= +92 kHz

f= +62 kHzf= +62 kHz

Longitudinal UNSTABLE Beam

Longitudinal STABLE Beam

Bunch Length is Uniform

Phase Modulationpresent.

Bunches are longer in the train centre.

Stronger Phase Modulation

Various Fillings: Phase Shift/Bunch Length/LandauVarious Fillings: Phase Shift/Bunch Length/Landau/Lifetime/Lifetime

These strak camera images show the different effect of 3HC on the beam between 90% filling (on the left) and uniform filling (on the right). The Landau damping effect is similar in both cases, the 90% filling shows the expected effect of the phase modulation along th ebunch train.



The best performance in terms of lifetime is obtained with a fractional filling of 96%. By further increasing the filling, the maximum obtained lifetime is lower, suggesting that the optimum setting for ELETTRA requires a small amount of “empty gap”.The 96% filling is now taken as the new standard filling pattern for User’s Operation Mode (320mA, 2.0GeV). In this condition 3HC is usually tuned from 1499.050 MHz (f=92kHz) to 1499.020MHz (f=62kHz).

Various Fillings: Various Fillings: Phase Shift/Bunch Length/Landau/Phase Shift/Bunch Length/Landau/LifetimeLifetime



Machine Upgrades and Ultimate Lifetime ValueMachine Upgrades and Ultimate Lifetime Value

During 2003 and 2004 several new vacuum chamber installations were performed. In June 2003 a new Aluminum-NEG coated chamber was installed in section ID10. In pre-3HC conditions the nominal lifetime was recovered at a dynamic pressure of about 10-11 mbar/mA. In the example of the ID10 chamber this took about 70 Ah, i.e. about 2,5 weeks operation.

In fact the ultimate lifetime with 3HC active, i.e. about 27 hours at 2.0 GeV 320 mA, was reached mid of September 2003, that is about 6 weeks of operation after the ID10 installation (there were 2 weeks shutdown in August).



• 3HC routinely in operation at Elettra• Stable Beam, refill every 36 hours• Operability and Reliability good• Careful maintenance to prevent faults,

recovery time can be long!• Experiments at different fillings confirm

expected effects (phase modulation, bunch lengthening)

• New standard filling set to 96%

ConclusionsConclusions

8th esls rf workshop daresbury 29-30 september 2004 super-3hc - m.svandrlik 1 g.penco, m.svandrlik...

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