CYCLOTRONS 2010 - List of Authors (Vanderlinden, T.)

Paper

Title

Page

Cyclotron Vacuum Model and H⁻ Gas Stripping Losses

200

V. Nuttens, M. Abs, J.L. Delvaux, Y. Jongen, W.J.G.M. Kleeven, L. Medeiros-Romao, M. Mehaudens, T. Servais, T. Vanderlinden, P. Verbruggen
IBA, Louvain-la-Neuve, Belgium

Many proton cyclotrons take the advantage of stripping for the extraction, by accelerating H⁻ ions. However, before extraction, the negative ion beam can suffer losses from stripping by the residual gas. The higher is the pressure, the higher the losses. Moreover, the stripped beam will be stopped on the inner wall of the cyclotron, inducing an additional degassing and increasing the pressure and hence losses in the cyclotron. For high beam current, degassing can be too large compared to the pumping capacity and the beam transmission can drop down to zero. The pressure inside the cyclotron has therefore a large impact on the current that can be extracted from the cyclotron. A simple model has been set up at IBA to determine the vacuum pressure in the hills and in the valleys of the Cyclone 70 cyclotron. The transmission is then computed by integration of the gas stripping cross-section along the ion orbits in the cyclotron. Pressure and transmission provided by the model are in good agreement with experimental data in the ARRONAX Cyclone 70 cyclotron installed in Nantes.

TUM2CCO04

Cyclone 70 Arronax Cyclotron - Commissioning Progress Report

L. Medeiros-Romao, M. Abs, J.L. Delvaux, S. Deprez, Y. Jongen, W.J.G.M. Kleeven, V. Nuttens, F. Peeters, M. Pinchart, T. Vanderlinden, S. Zaremba
IBA, Louvain-la-Neuve, Belgium

The development of the Cyclone® 70, started at the end of 2005. The installation began in March of 2008 and the testing in July of the same year. The injection phase was a rapid success leading to beam acceleration and extraction. The latter presented major hurdles that were overcome with success, notwithstanding an impact on the foreseen schedule. On one side, the alpha and proton acceleration faced a harmonic one field component primarily considered negligible during the mapping. This was resolved by shimming of the iron and the introduction of harmonic coils. Moreover, the extraction of the full alpha intensity required a redesign of the deflector which was limited by its power dissipation capabilities. On the other hand, the proton beam extraction, 750 μA at 70 MeV, was the last major hurdle, given the vacuum and outgassing levels with high intensity beams. After an important diagnostics phase and vacuum calculations, modifications were implemented aiming the full performances. Meanwhile, the ARRONAX team started their activities and produced the first radioisotopes using this unique and powerful tool set for a wide horizon of present and future nuclear medicine applications.

Slides TUM2CCO04 [4.105 MB]

Paper	Title	Page
MOPCP075	Cyclotron Vacuum Model and H⁻ Gas Stripping Losses	200
	V. Nuttens, M. Abs, J.L. Delvaux, Y. Jongen, W.J.G.M. Kleeven, L. Medeiros-Romao, M. Mehaudens, T. Servais, T. Vanderlinden, P. Verbruggen IBA, Louvain-la-Neuve, Belgium
	Many proton cyclotrons take the advantage of stripping for the extraction, by accelerating H⁻ ions. However, before extraction, the negative ion beam can suffer losses from stripping by the residual gas. The higher is the pressure, the higher the losses. Moreover, the stripped beam will be stopped on the inner wall of the cyclotron, inducing an additional degassing and increasing the pressure and hence losses in the cyclotron. For high beam current, degassing can be too large compared to the pumping capacity and the beam transmission can drop down to zero. The pressure inside the cyclotron has therefore a large impact on the current that can be extracted from the cyclotron. A simple model has been set up at IBA to determine the vacuum pressure in the hills and in the valleys of the Cyclone 70 cyclotron. The transmission is then computed by integration of the gas stripping cross-section along the ion orbits in the cyclotron. Pressure and transmission provided by the model are in good agreement with experimental data in the ARRONAX Cyclone 70 cyclotron installed in Nantes.

TUM2CCO04	Cyclone 70 Arronax Cyclotron - Commissioning Progress Report
	L. Medeiros-Romao, M. Abs, J.L. Delvaux, S. Deprez, Y. Jongen, W.J.G.M. Kleeven, V. Nuttens, F. Peeters, M. Pinchart, T. Vanderlinden, S. Zaremba IBA, Louvain-la-Neuve, Belgium
	The development of the Cyclone® 70, started at the end of 2005. The installation began in March of 2008 and the testing in July of the same year. The injection phase was a rapid success leading to beam acceleration and extraction. The latter presented major hurdles that were overcome with success, notwithstanding an impact on the foreseen schedule. On one side, the alpha and proton acceleration faced a harmonic one field component primarily considered negligible during the mapping. This was resolved by shimming of the iron and the introduction of harmonic coils. Moreover, the extraction of the full alpha intensity required a redesign of the deflector which was limited by its power dissipation capabilities. On the other hand, the proton beam extraction, 750 μA at 70 MeV, was the last major hurdle, given the vacuum and outgassing levels with high intensity beams. After an important diagnostics phase and vacuum calculations, modifications were implemented aiming the full performances. Meanwhile, the ARRONAX team started their activities and produced the first radioisotopes using this unique and powerful tool set for a wide horizon of present and future nuclear medicine applications.
	Slides TUM2CCO04 [4.105 MB]