Participants: Peter Butler, Pierre Delahaye, Thomas
Sieber,
Mats Lindroos (chair), Fredrik Wenander, .
1. General Issues
-
Members of the vacuum and alignment
group shall be invited to one of the next REX meetings to define the work at REX
during the next shutdown. The status of the vacuum system is basically the same as during the startup in 2001. Realignment is definitely necessary in several sections of the
machine.
-
Elias
Villar Gomez has started to collect all the drawings of the REX components. Thomas will contact
-
A
summary of the Ni run last week has been written and can be found attached to
these minutes.
-
Thomas
distributed his
final update of
the 2005 REX
budget. There are
30 kCHF left on the T131900 account as well as 30 kCHF on the physics group account. The
-
A
member of the AB-RF-LR group should participate in the REX meetings in the future. Thomas will
talk to Maurizio Vretenar concerning this.
-
Starting on Tuesday 17.05.,
we will have a daily short REX meeting at 16.00 in the ISOLDE kitchen to
discuss the startup and the status of the running Xe experiment.
-
2. Current REX Experiment. TRAP
-
Trap injection worked out well, showing an efficiency
of about 50%.
-
We
use the 68Cu19+ (A/q=3.579) and 70Cu19+ (A/q=3.684). EBIS efficiency is at 17%.
-
The
Linac has been scaled from 70Ni to the Cu. After reducing the energy to 2.8 MeV/u, transmission and spot were worse than during the Ni run. Since retuning would take a
lot of time the measurements continue at about 50% transmission.
-
The
Cu run will continue until Tuesday morning.
-Pierre
-
and Fredrik had the problem of discharges in
the trap, means there was more current measured at the exit than injected from
the test source. Nicolas David found a broken cable at a transfer element. The
bad contact was responsible for the discharges.
-The test ion source ’runs stable now after the
regulation has been improved.
-The application for the frequency scan of the trap
has to be improved.
3. TrapEBIS
-
The
control system of
the trap will be
upgraded after the Cu
run. After the current experiment there will be some test runs for continuous
injection into the EBIS as well as for injection with rotating wall cooling.
-The bad transmission through
the mass separator, which has been observed on Thursday, was partially caused
by two switched cables in one of the steerers.
-There was again a problem
with the cabling of the Wago module for the high voltage cassettes, which could
be repaired by Nicolas.
-The transmission through the
separator is at the moment 70- 80%, due to the
high residual gas pressure, the current is about a factor 10 higher than usual.
-Stable beam for Linac
optimization will be available on Monday.
-The baking after the run will
be done now with the old NEG strips.
-One day is needed to optimize
beam transport through the BTS.
-Dry injection (without
electron beam and magnetic field) into the EBIS is still problematic because of
the high noise level on the electrodes.
4. EBISLinac
- The EBIS cathode is behaving very well, so the question was raised if we should skip the cathode change scheduled for mid August.
-
A Finnish student, Pekka Suominen will work together with
Fredrik and Pierre on some charge breeder tests
during
the following months.
-
-
BERTRONIX could not solve the
principle problem of the limited power level of the 200 MHz amplifier. Also the
unstable operation at 10% duty cycle is still a problem. The amplifier could be
tuned to ~100kW output power on a dummy load. It is running quite stable now at
30Hz, 600us. So we can expect closed loop operation on the cavity at about 85
kW.
54. LinacControl
System
-
The
problems with the
200 MHz amplifier are still not solved. At the moment we have a reasonably stable
operation at 10 Hz and 60 kW output power. We had to reduce the pulse length to 300 us,
reduce the anode voltage to 14 kV and delicately adjust the grid voltages. This means we are running at
less than 60% of the nominal power level and at a duty cyle of 0.3% (design: 10%). It should be possible to
continue in this way until the end of the running period.
-
With
the current mode of operation of the 200 MHz amplifier we can provide a 2.8 MeV/u beam for
an A/=3.6 beam at a repetition rate of max. 10-15 Hz. It has to be decided if
this is acceptable for the upcoming runs, means if it is possible to reach the required
charge states.
-
Thomas will have a meeting next week with people from AB-RF and Mr.
Pirkl to discuss current operation of the amplifier and long term repair plans.
6. Control System
-
The
rf-control application done by Nikolai is performing very good, allowing automatic restart
of the amplifiers, automatic A/q scaling, data saving, diagnostics of the rf-systems etc. Also the new FESA system on
which the rf-control is based is running nicely
stable since more than a week.
-
Nikolai
reports that the control system for the power supplies is in principle in the same stadium as the
rf-control system.
For the power supplies development of control software in the OP group is required.
-The BD FEC is still stopping
from time to time, Sylvestre Catin has been
informed about this.
-Nikolai found that there are
not enough Ethernet connections in the network rack, where he wants to connect
his Front end computer.
Minutes by Thomas