HESR 2 Electron Cooling

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HESR 2 Electron Cooling

• Björn Gålnander
• The Svedberg LaboratoryUppsala University

Midterm Review, DIRACsecondary-Beams December 8,
2006 GSI, Darmstadt
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Outline

• HESR Electron cooler
• Present project status
• Outlook

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High Energy Storage Ring
HESR is presently being designed in a consortium
formed between FZ-Jülich, GSI and UU The
electron cooler is the main responsibility of
Uppsala University.

• Antiproton momentum, 1.5 15 GeV/c
• Cooling to counteract PANDA pellet target
• Electron cooling up to 8.9 GeV/c(4.5 MeV
  electron energy)
• Stochastic cooling above 3.8 GeV/c

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HESR Electron Cooler
Parameters for the HESR cooler

• The cooling force needs to be stronger than at
  Fermilab to counteract the internal target
• Higher magnetic field
• Better straightness

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Objective of Design Study
Task 12, HESR 2 Electron cooling Description of
work An important part of the work will be to
construct prototypes of several critical parts of
the system. The exact content of the prototyping
work will be determined in the course of the
study. The CELSIUS electron cooling system, which
will then be taken out of use for its purpose at
the CELSIUS ring, will be used as a test bench,
and will be used to test electron beam diagnostic
equipment as well as to make tests related to the
high-voltage behaviour of the system. Other
aspects of the electron cooling system, including
the method to charge the high-voltage terminal,
the problems to create the required quality of
the magnetic field and stability of the high
voltage, the required ultra-high vacuum and the
electron beam optics and stability of the
electron beam transport will be investigated. In
the final report all experience will be
summarized, drawings will reflect the status of
the component development, and a first design of
a control system for this high power device will
be suggested on the basis of the accumulated
experience.
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Present Project Plan

• Different sub-projects, responsible persons
• Design high-voltage column G. Norman, A
  Shemyakin
• Test prototype high-voltage solenoid G. Norman
• Design magnet system for electron beam transport
• K. Rathsman, D. Reistad
• Design and test magnet field measurement
  system T. Bergmark
• Design vacuum chamber, make prototype T.
  Bergmark, O. Byström
• Design and test prototype scraper B. Gålnander,
  T. Lofnes,
• Design electron gun and collector G. Norman
• Tests on high-voltage regulation at Uppsala
  Tandem Pelletron T. Bergmark

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High Voltage Column
Collector
Gun
Pellet chain
HV solenoid
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Magnet system

• Sections of 3 metres (24 m total length)
• Pancake coils (normal conducting), individually
  adjustable to achieve 10 µrad rms straightness

• Deliverable 29, Report on solenoids and toroids,
  delayed
• Design revised, making coils smaller and less
  expensive, saving about 30 of copper.
• Superconducting alternative is also considered

• Scraper and pick-up electrodes.
• Horizontal and vertical dipole windings.

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Magnetic Field Measurement System
needed for pancake alignment

• Prototypes are being manufactured
• Test will be performed during 2007

Measurement carriageand sensor head
Prototype test set-up
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Vacuum Chambers

• with rails for the Magnetic Field Measuring System

Test tube of 1 m, two sections of 2.8 m will be
delivered week 5, 2007
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Scraper tests at the CELSIUS cooler
Modification of CELSIUS cooler for scraper tests
with electron beam
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Outlook

• During spring 2007 several prototype tests will
  take place
• Autumn 2007, test evaluation and final report
  work
• No overall delay expected, HESR 2 will be
  finished by Feb. 2008.
• However, the Deliverable D29, Report on
  solenoids and toroids, is delayed until 1 March,
  2007, since this sub-project has been given more
  weight compared to the original planning.

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Present group members
Dag Reistad, Task Leader Torsten Bergmark Björn
Gålnander, Deputy Tomas Johnson Tor Lofnes Gunnar
Norman
Olle Byström Stefan Johnson Tord Peterson Karin
Rathsman
Collaboration with IKP (Ziemann, beam dynamics),
MSL (Danared, magnetic field calculations), BINP
Parkhomchuk et al., Fermilab, A. Shemyakin et al.
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Thank you!
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Layout
8 MeV tank
4.5 MeV tank
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CELSIUS electron cooler

• Low energy cooling is a well established
  technique.
• CELSIUS cooler was used to cool protons and ions
  up to 500 MeV/nucleon

Principle of electron cooling
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Pick-up Electrodes and Scrapers
are combined in one unit
Pick-up electrodes To measure positions of
antiproton and electron beams with resolution of
10 µm. Scrapers To measure envelope oscillations
of the electron beam.