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
2
Start:
Month 1
Finish:
Month 15
Cost:
Title:
WP2:
Design
and Construction of Ion beam strippers
Description:
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
Deliverables:
1
Report and possibly part of BS, MS or PhD thesis
WP2: Table of Activities in progress
Completed
Activity
Target 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)
Charge analysis program TARDIS
(Transmitted
chARge DIStribution)
used for foil and gas stripping by Myrto Asimakopoulou written
in
- for details HNPS2014:
Proceedings
TARDIS output: 12 MeV C charge state stripping analysis
Video
(MTS file - 370MB) showing phase development over time for C=33.3uF
and V=17.5V (chan 1 showing point 6, chan 2 showing point 7).
On the left is shown the current flowing in the primary of the
toroidal transformer. Points 6 and 7 are shown on the pdf of the
Steinmetz connection diagram (just before)
Powerpoint information reference booklet with notes showing
details of Kansas State University (KSU) gas terminal stripper
arrangement
How to obtain Li ions from the sputter source
WP2: References
Κύκλωμα
Steinmetz - Μετατροπή μονοφασικού σε τριφασικό με έναν μόνο
πυκνωτή!
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
Hans-Dieter Betz, Charge Equilibration of High-Velocity
Ions in Matter, in Atomic Physics: Accelerators, Methods
of Experimental Physics, vol. 17, ed. P Richard, (Academic Press,
NY, 1980), Chapt. 3, pp. 73-88.
K. Shima, N. Kuno, M. Yamanouchi, and H. Tawara. Atomic Data
and Nuclear Data Tables, 51(2), (1992).
V. S. Nikolaev and I. S. Dmitriev, Physics Letters, 28A(4) (1968)
Wenjie Liu et al., CHARGE STATE STUDIES OF HEAVY
IONS PASSING THROUGH GAS, MS Thesis, Simon Fraser University,
2001
Zamkov et al., Energy dependence of the metastable
fraction in B3+(1s21S,1s2s 3S)
beams produced in collisions with thin-foil and gas targets,
Phys.
Rev. A 64 (2001) 052702
Benis et al., Technique for the determination of
the1s2s 3S metastable fraction in two-electronion beams,
Phys.
Rev. A 65 (2002) 064701
Benis et al., Elastic resonant and nonresonant differential
scattering of quasifree electrons
from B4+(1s) and B3+(1s2) ions,
Phys.
Rev. A 69 (2004) 052718
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
Completed
Activity
Target 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.
