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   Project Coordinator
   Prof. Theo Zouros
   Atomic & Molecular Physics
   Dept. of Physics
   Univ. of Crete, PO Box 2208,
  . GR-71003 Heraklion
   e-mail: tzouros@physics.uoc.gr

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Home > Work Packages > WP2 - Ion Strippers
Work Packages

Work Packages: WP1  WP2  WP3  WP4  WP5  WP6  WP7  WP8  WP9  WP10  WP11  WP12 Timetable

Work Package 2: Design and Construction of Ion beam strippers

Figure 1: Photo of Tandem terminal stripper showing stripper canal housing and gas bottle.

Figure 2: Photo of KSU Tandem terminal stripper showing stripper canal housing and turbo.


Figure 3: Photo of KSU Tandem terminal stripper showing the lid cover of the canal housing with gas inlet, bottle and manometer.


Figure 4: Schematic of poststripper chamber showing beam line and vacuum equipment to be used



Figure 5: Photo of 400Hz 125V to 20V toroidal transformer to power recirculating gas turbo from terminal



Figure 6: Photo of terminal gas stripper details (from left to right): (1) Housing with new turbo and recirculating copper tubing, (2) Gas kanal installed with two gas inlets shown: one for the gas bottle feed and the other for the recirculating gas feed, (3) Box closed inside terminal - foil stripper control unit shown sitting on top, (4) Turbo and gas bottle (red) with copper tubing replaced by swagelock thinner tubing with a piggy tail twist to allow for extra stress to be absorbed.


Figure 7: Photos from the installation of the post stripper station (between analyzing and switching magnet) which included both a foil stripper and a gas stripper with turbo pump and baffels. Also seen is the beam profile monitor installed just before the post stripper chamber, the two large isolation valves which acted as baffles (they had a small hole in them to allow the beam to go trhough) to better isolate the post stripper gas from the rest of the beam line and the turbo pump used for differential pumping. The finished installation is seen lower right.


Figure 8: Photos from the post stripper. (Top) Foil stripper showing foil holder on rod. (Bottom - Left) Gas cell of gas post stripper on support sturcture. (Bottom - Right) View from the top of 6-way cross housing gas and foil post stripper.


WP2: Description of work package

Work Package



Month 1


Month 15



WP2: Design and Construction of Ion beam strippers


Research Teams:

RT1, RT2, RT3

2.1 Foil post stripper design and construction: A self-supporting multiple foil stripper will be designed, build in the shop and placed between analyzing and switching magnet for post-stripping of the beam.

2.2 Tandem terminal gas stripper design and construction: The TANDEM tank will be opened and a differentially pumped gas canal will be positioned with turbo pump, pressure monitor and leak valve.

2.3 TRANSPORT study of beam transmission through strippers: Code TRANSPORT will be used for the optimization of the low energy TANDEM beam for optimal transmission through the terminal stripper

2.4 Implementation of charge state analysis code for optimal charge selection:. Charge state analysis code CHARGE implemented for the TANDEM parameters to predict charge distributions after stripping. 

2.5 Test of strippers and ion transmission to new beam line: Test beams run to measure the efficiency of gas and post stripping and get a better idea of the actual beam currents of highly charged ion beams


1 Report and possibly part of BS, MS or PhD thesis

WP2: Table of Activities in progress

CompletedActivityTarget Date
Collect information about recirculating gas terminal strippers at KSU and Argentinian tandem
Apr 2013
Checked for correct terminal georator power for turbo
May 2013
Ordered and received Leybold 250 lt/s turbo without controller to be installed inside the terminal
Jun 2013
Opened Demokritos tandem terminal to study existing arrangement
Dec 2013
Removed gas stripper supply bottle and arranged to have it replaced
Dec 2013
Install foil post stripper between analyzing and switching magnet - still need to adjust length of foil holder arm - only one set of target foils presently accessible
Feb 2014
Charge state analysis Fortran and C# code set up with tandem parameters to be used for highly charged ion beam selection
Jul 2014
Design and have build 400 Hz 125V to 12-42V transformer to power recirculating turbo pump (Stavrou company build it - still being tested)
Oct 2014

Open TANDEM terminal and test 400 Hz 125V to 12-42V transformer proper operation with turbo prior to putting inside terminal

Best combination found: U=17.5V, C=33.3μF - see video (Technical Notes below)

Nov 2014
Machine shop flange for mounting terminal turbo
Jan 2015
Install Steinmetz circuit and toroidal transformer
Feb 2015
Build gas post stripper in machine shop based on existing design
Jan 2015
Adapt KSU tandem stripper canal design to Demokritos tandem
Nov 2014
Install new customized 4" 6-way cross to house post-strippers, move BPM1 and add 4" Tees before and after gas post stripper for future vacuum improvement. Optically Align BPM1 and gas post stripper
May 7-8 2015
Mount turbo pump on terminal gas stripper box housing
May 2015
Install Steinmetz circuit for powering terminal gas stripper turbo (final choice: U=17.5V, C=35μF)
May 2015
Install and align gas kanal for terminal gas stripper
May 2015
Check vacuum of terminal stripper box with new turbo and gas stripper tube connections
May 2015
Test turbo operation with installed Steinmetz circuit power
May 2015
Replace bottle and check gas system thermal leak valve
June 2015
Test recirculating gas stripper supply and pressure control (leak found in recirculating gas tubing when pressurizing tank with SF6 - under investigation - new tubing build and is undergoing testing)
June 2015
Test foil post stripper with ion beam
Nov 2015
Test gas post stripper with ion beam
Nov 2015
Test recirculating gas terminal stripper
Dec 2015
Final Report on work package completed
Dec 2015

WP2: Deliverables

Additional related results:

WP2: People involved

  • Prof. Theo Zouros - MRG RT1
  • Dr. Sotiris Harissopulos - MRG RT2
  • Dr. Tasos Lagoyannis - MRG RT2
  • Dr. Mihalis Axiotis - GEC RT2
  • Miltos Andrianis - GEC RT2
  • Prof. Theo Mertzimekis - GEC RT2
  • Manolis Tsopanakis - GEC RT2
  • Dr. Tasos Dimitriou - GEC RT1
  • Giannis Madesis - GEC RT1
  • Myrto Assimakopoulou (student technical assistance) - GEC RT2
  • Aggelos Laoutaris (MS student) - GEC RT1

WP2: Technical Notes

WP2: References

  • Κύκλωμα Steinmetz - Μετατροπή μονοφασικού σε τριφασικό με έναν μόνο πυκνωτή!
  • Electrostatic Accelerators - Fundamentals and Applications R. Hellborg (editor) (Springer 2005) pp. 620.
    In particular:
    • Chapter 10 - D. Weisser, Stripper Systems, pp. 166-180
    • Box 5 - H.J. Whitlow, H. Timmers, Charge Exchange and Electron Stripping, pp. 181 - 186.
    • Box 6 - V. Liechtenstein, Carbon Stripper Foils - Preparation and Quality, pp. 187- 191.
  • Jorge O. Fernandez Niello et al., A study of the tandem-terminal-stripper reaction 1H(12C,c)13N
    with accelerator mass spectrometry,
    Nuclear Instruments and Methods in Physics Research B 240 (2005) 495 - 499
  • P. Repnow et al., The Heidelberg MP tandem Van de Graaff, Nuclear Instruments and Methods 122 (1974) 179-189
  • Peng Shixiang et al., A NEW GAS STRIPPER DESIGN FOR PKUAMS, Proceedings of the 2nd Asian Particle Accelerator Conference, Beiging, 2001, p. 893-895
  • D E Alvarez et al., Design of a New Terminal Gas Stripper System, p. 261-268
  • Madis Kiisk, Bengt Erlandsson, Mikko Faarinen, Ragnar Hellborg, Kjell Hakansson, Per Persson, Goran Skog, Kristina Stenstrom, The charge state distribution of a carbon beam measured at the Lund pelletron accelerator with the newly installed terminal pumping system in use, NIMPRA481 (2002) 1-8
  • Transformers

Work Package 2 ( continued): after end of THALIS grant (31/12/2015)


Figure 9: Pump down times for HDA chamber.

WP2: Table of Activities in progress

CompletedActivityTarget Date
Final implementation of gas terminal stripper - no leaks observed
Jun-Aug 2016
First test of metastable fraction with 12 MeV C4+ beam using gas terminal stripper. Smaller fractions observed. Tests of stability of fraction not yet conclusive
Sep 2016
Further tests on the stability of gas pressure of the terminal stripper and the stability and reproducibility of measured metastable beam fractions.
Dec 2016
Further tests on the stability of gas pressure of the post stripper and the stability and reproducibility of measured metastable beam fractions.
Jan 2017

Last Update: 29/01/17 19:55:14

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