HERA Technical Improvement Program M. Bieler, DESY, 5.11.2005

DESY MAC, 9.11.2005

M. Bieler, DESY, -MBB- 1

HERA Technical Improvement Program

M. Bieler, DESY, 5.11.2005

- Replacement of aging Components- Performance Improvements- Reliability Enhancements

DESY MAC, 9.11.2005


The BU Coil Exchange Program

p-Ring

e-RingCoils are made from hollow copper bars. At the rectangular joints turbulent water flow creates leaks.

BU dipolemagnet

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Old BU Coils

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RF WaveguidesRF Cavity

BU Magnet(21 tons)

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3 BU magnets,6 new coils (Oct. 03),no old coils

N

E

S

W

3 BU magnets,1 new coil (July 03),5 old coils

3 BU magnets,2 new coil (April 05),4 old coils

3 BU magnets,6 old coils



HERA

All old coils will be replaced in the next winter shutdown

DESY MAC, 9.11.2005


Electron RF System Improvements

Problem:Crowbar system for rf klystronsmisfires often.Solution:More currenttransformers,signals combinedin a new crowbar ignition logic.

Successfully tested in 1 of 8 rf stations.Installation in all stations in the shutdown.

DESY MAC, 9.11.2005


Longitudinal Multi Bunch Damper System for Protons

Problem: Proton bunch length increases on the ramp, driven by longitudinal multi bunch instabilities. Longer bunches decrease the luminosity (hour glass effect).

Analysis: Different modes drive the instabilities.

Solution: Broadband damper system.

DESY MAC, 9.11.2005


Longitudinal Multi Bunch Damper System for Protons

Cavity, transmitter and electronicsready for installation in the shutdown.

DESY MAC, 9.11.2005


Vacuum System Improvements

HERA e Spin Rotator

Due to the vertical bendsin the spin rotator some vacuum chambers see high synchrotronradiation loads.

The bellows between the vacuum chambers are protected againstdirect radiation by absorbers, but go through thermal cycles with the beam current.

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Typical leak of a rotator bellow:End of a luminosity run, dump of 5mA electrons,2 minutes later the vacuum pressure increases.

DESY MAC, 9.11.2005



Vacuum weld(breaks underthermal stress)

Support weld(often missing)

Solution:Open vacuum weld, add support weld,redo vacuum weld.To be done on all 24 bellows in thewinter shutdown.

DESY MAC, 9.11.2005



Increased Pumping power in RF section:A number of new vacuum pumps with higher pump speed have been purchased and will be installed in the cavitysection HERA SR. Here the vacuum has to be ventedanyway to replace two input couplers. The stronger pumps will help to minimize the time neededfor rf conditioning of this section.

DESY MAC, 9.11.2005


Permit ServerEvery now and then someone tries to accumulate protons…

Therefore we need a rather intelligent system to prevent us from (for example) injecting protons into an alreadyoccupied bucket.

Such a system was planned for a long time, but only nowprocedures are stable enough to control them.

Phase 1 of the new Permit Server checks all necessary conditions for proton and electron transfer from PETRA to HERA.

DESY MAC, 9.11.2005


Permit ServerIf any of the givenconditions is not fulfilled,the transfer is blocked.

This can be overruledby the operator.

The Permit Server will be upgraded to cover the whole HERA procedure.

DESY MAC, 9.11.2005


p Tune ControllerA new proton tune controller is operational for most of the ramp.Problems are-Coupling-Chromaticity-Peak detection A different version for luminosityoperation is under test.Peak detection by wavelets is more reliable.

DESY MAC, 9.11.2005


Automated Timing SystemThe following features of the HERA Timing System have been automated:

- Electron timing: Bunch position relative to a marker.- Proton timing: Bunch position relative to a marker.- E/P timing: E and p frequencies locked and bunches colliding at the IP.

All this had to be checked and corrected by the operators and is now handled automatically in the background.

DESY MAC, 9.11.2005


BPMs

e-BPMs:New BPM electronics is installed at all monitors since 2004.New software features like post mortem analysis are in preparationsince then.

p-BPMs:The old p-BPM system is getting more and more unreliable. NewBPM electronics will be installed at the 12 most critical BPMs in thestraight sections north, east and south.

e Orbit Stabilizer:The new e-BPM electronics allowed the introduction of a globalorbit stabilization system. This system has been improved eversince and is vital for stable luminosity operation.

DESY MAC, 9.11.2005


Fast Electron Orbit Feedback

Feedback:8 corrector coils will be used for closed orbit bumps in both IPs inboth planes. Up to frequencies of 20Hz a reduction of the orbitmotion should be possible. First tests foreseen for November 2005.

FFT of fast orbit motion,measured with one BPM.Peaks at 50Hz and lowfrequencies, amplitudes40 to 100µm.

DESY MAC, 9.11.2005


Machine Protection System

Fast Magnet Current Measurement:A fast current measurement has been implemented in some critical power supplies. Sudden drops of the power supply voltage are detected and lead to a beam dump before the beam reacts on the change in the magnetic field.

Fast Beam Current Measurement:A fast beam current measurement has been implemented. Sudden drops in beam current are detected and lead to a beam dumpbefore the rest of the beam is lost.

These systems are faster than the beam loss monitors and have helped to prevent contamination due to fast proton losses.

DESY MAC, 9.11.2005


Synchrotron Light Monitors

p Synchrotron Light:A Synchrotron Light Monitor for protons at 920GeV has been developed and installed at a vertically bending BU magnet. It allows continuous emittance measurements

e Synchrotron Light:The Synchrotron Light Monitor for electrons has been improved and allows continuous emittance measurements now.

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Other DiagnosticsLifetime Measurement:A new algorithm for a fast lifetime measurement was implemented. It gives faster response to sudden changes in the beam conditions.

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Other DiagnosticsTemperature Measurement:After a stainless steel vacuum chamber had been destroyed bysynchrotron radiation, a new kind of very thin temperature sensorshas been put between the chamber and the surrounding quadrupole magnet. The sensors are connected to the electron beam dump.

DESY MAC, 9.11.2005


SummaryA rich program of 1.5 M€ and 10 PY is under way to improve HERA’s performance and keep the machinereliable until the very last day of operation.

Acknowledgement:This talk covers the work of many people from MEA, ZBAU, MIN, MSK, MDI,MST, MPY, MHE, MHF, MVA,…

Documents

HERA Technical Improvement Program M. Bieler, DESY, 5.11.2005