HERA Technical Improvement Program M. Bieler, DESY, 5. 11. 2005 - Replacement of aging Components - Performance Improvements - Reliability Enhancements DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 1
The BU Coil Exchange Program p-Ring e-Ring BU dipole magnet DESY MAC, 9. 11. 2005 Coils are made from hollow copper bars. At the rectangular joints turbulent water flow creates leaks. M. Bieler, DESY, -MBB- 2
The BU Coil Exchange Program Old BU Coils DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 3
The BU Coil Exchange Program BU Magnet (21 tons) RF Cavity RF Waveguides DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 4
The BU Coil Exchange Program 3 BU magnets, 6 new coils (Oct. 03), no old coils N 3 BU magnets, 1 new coil (July 03), 5 old coils 3 BU magnets, 6 old coils W 3 BU magnets, 2 new coil (April 05), 4 old coils DESY MAC, 9. 11. 2005 HERA E 3 BU magnets, 6 old coils All old coils will be replaced in the next winter shutdown S 3 BU magnets, 6 old coils M. Bieler, DESY, -MBB- 5
Electron RF System Improvements Problem: Crowbar system for rf klystrons misfires often. Solution: More current transformers, signals combined in 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 M. Bieler, DESY, -MBB- 6
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 M. Bieler, DESY, -MBB- 7
Longitudinal Multi Bunch Damper System for Protons Cavity, transmitter and electronics ready for installation in the shutdown. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 8
Vacuum System Improvements HERA e Spin Rotator Due to the vertical bends in the spin rotator some vacuum chambers see high synchrotron radiation loads. The bellows between the vacuum chambers are protected against direct radiation by absorbers, but go through thermal cycles with the beam current. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 9
Vacuum System Improvements Typical leak of a rotator bellow: End of a luminosity run, dump of 5 m. A electrons, 2 minutes later the vacuum pressure increases. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 10
Vacuum System Improvements Vacuum weld (breaks under thermal stress) Support weld (often missing) Solution: Open vacuum weld, add support weld, redo vacuum weld. To be done on all 24 bellows in the winter shutdown. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 11
Vacuum System Improvements 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 cavity section HERA SR. Here the vacuum has to be vented anyway to replace two input couplers. The stronger pumps will help to minimize the time needed for rf conditioning of this section. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 12
Permit Server Every 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 already occupied bucket. Such a system was planned for a long time, but only now procedures 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 M. Bieler, DESY, -MBB- 13
Permit Server If any of the given conditions is not fulfilled, the transfer is blocked. This can be overruled by the operator. The Permit Server will be upgraded to cover the whole HERA procedure. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 14
p Tune Controller A new proton tune controller is operational for most of the ramp. Problems are -Coupling -Chromaticity -Peak detection A different version for luminosity operation is under test. Peak detection by wavelets is more reliable. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 15
Automated Timing System The 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 M. Bieler, DESY, -MBB- 16
BPMs p-BPMs: The old p-BPM system is getting more and more unreliable. New BPM electronics will be installed at the 12 most critical BPMs in the straight sections north, east and south. e-BPMs: New BPM electronics is installed at all monitors since 2004. New software features like post mortem analysis are in preparation since then. e Orbit Stabilizer: The new e-BPM electronics allowed the introduction of a global orbit stabilization system. This system has been improved ever since and is vital for stable luminosity operation. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 17
Fast Electron Orbit Feedback FFT of fast orbit motion, measured with one BPM. Peaks at 50 Hz and low frequencies, amplitudes 40 to 100µm. Feedback: 8 corrector coils will be used for closed orbit bumps in both IPs in both planes. Up to frequencies of 20 Hz a reduction of the orbit motion should be possible. First tests foreseen for November 2005. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 18
Machine Protection System Fast Beam Current Measurement: A fast beam current measurement has been implemented. Sudden drops in beam current are detected and lead to a beam dump before the rest of the beam is lost. 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. 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 M. Bieler, DESY, -MBB- 19
Synchrotron Light Monitors e Synchrotron Light: The Synchrotron Light Monitor for electrons has been improved and allows continuous emittance measurements now. p Synchrotron Light: A Synchrotron Light Monitor for protons at 920 Ge. V has been developed and installed at a vertically bending BU magnet. It allows continuous emittance measurements DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 20
Other Diagnostics Lifetime Measurement: A new algorithm for a fast lifetime measurement was implemented. It gives faster response to sudden changes in the beam conditions. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 21
Other Diagnostics Temperature Measurement: After a stainless steel vacuum chamber had been destroyed by synchrotron radiation, a new kind of very thin temperature sensors has been put between the chamber and the surrounding quadrupole magnet. The sensors are connected to the electron beam dump. DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 22
Summary A rich program of 1. 5 M€ and 10 PY is under way to improve HERA’s performance and keep the machine reliable 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, … DESY MAC, 9. 11. 2005 M. Bieler, DESY, -MBB- 23
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