Accelerators – Reports 3

REPORTS

Van de Graaff Accelerator

A new console program was installed to display all the beam lines and their diagnostic components, focusing and steering elements visually (see Figure 4 below), such that all the parameter settings and read back values are continuously visible. The program also indicates the status of the elements by means of colour coding. For example, the colour displayed on the beam line image shows the position of the beam and which line is selected.

A computer safety-interlock program has also been installed. This program protects personnel, i.e. it switches the beam off when unsafe conditions arise, and it also protects beam line elements and power supplies against various unsafe conditions. Another feature of the program is that it records the date and time for both input and output occurrences. This is useful to determine any pattern of unsafe conditions that could occur. 

Development work on a microwave ion source that was undertaken for an M.Sc. thesis submitted at the beginning of 2007, indicated that the source could be very useful for Van de Graaff accelerators because of its reliability, ease of use, the fact that it does not use a filament, and does not require cooling. The source also produces higher beam currents than those presently in use at the Van de Graaff accelerator. A proton beam current of 70 μA has been obtained from the source.

Table 3 below shows that beam time on target increased and the time for maintenance decreased after the largest part of the refurbishment of the accelerator was completed. Stability of the beam current has also improved.

Year

1999

2000

2001

2002

2003

2004

2005

2006

Beam on target (hours)

3606

4016

3381

3560

1635

4700

4527

6404

Maintenance/Conditioning (hours)

587

2457

479

3212

2331

2329

2360

1457

Development (hours)

88

638

1886

776

Table 3: The beam statistics of the van de Graaff accelerator

 

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screendump1

Figure 4: A computer screen display of the interlock system

 

Publications

M. Sakildien, D.T. Fourie , J.G. de Villiers, J.L. Conradie, P.J. Celliers, J.L.G. Delsink, R.E.F. Fenemore, R.H. McAlister, C. Lussi. The iThemba LABS Cyclotrons and Their Beams.  51st South African Institute of Physics Annual Conference, University of the Western Cape, 3-7 July 2006.

C.L. Ndlangamandla, P.J Celliers, J.J. Kritzinger, J.L. Conradie and O.M Ndwandwe. The Development and  Improvement of a Microwave Ion Source at iThemba LABS. 51st South African Institute of Physics Annual Conference, University of the Western Cape, 3-7 July 2006.

D.T. Fourie, J.L. Conradie, J.V. Pilcher, I.Z. Machi, J.G. de Villiers, M.F. Jakoet, O. Pekar, I.H. Kohler, L.G. Masher, C. Lussi, J.L.G. Delsink, E.W. Rood, M.J. Labuschagne, R.H. McAlister, F.M. Smith, J.P.A. Crafford and P.A. van Schalkwyk. Upgrading of the iThemba LABS (Gauteng) EN Tandem Accelerator and Beam Lines. 51st South African Institute of Physics Annual Conference, University of the Western Cape, 3-7 July 2006.

Continuous Beam Phase Measurement in a 200 MeV Cyclotron, J.L. Conradie, P.F. Rohwer, D.T. Fourie, A.H. Botha, P.J. Celliers, J. Van Niekerk, H. Du Toit, iThemba LABS, P. O. Box 722, Somerset West 7130, South Africa, J. Dietrich, I. Mohos, Forschungszentrum Jülich, Postfach 1913, D-52425 Jülich, Germany, Proceedings of the 10th European Particle Accelerator Conference (EPAC’2006), UK, Edinburgh, 26-30 June 2006.

 

Postgraduates

Mr. C.L. Ndlangamandla, M.Sc.-thesis, January 2007, University of Zululand: The Development and Improvement of a Microwave Proton Ion Source at iThemba LABS.

 

Reference

Grenoble Test Stand (GTS): A Multipurpose Room Temperature ECRIS. D.Hitz et all, 15th International Workshop on ECR Ion Sources, June 2002, University of Jyväskylä

 

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