Dégazage des solides en ultravide : quelques notions de base pour les techniciens du CERN

Tout matériau mis sous vide relâche du gaz préalablement inclus lors des processus de production et pendant l’exposition à l’air atmosphérique. En fonction de la nature du gaz et des matériaux utilisés en ultravide, le taux de dégazage peut couvrir plus de 10 ordres de magnitude. Par conséquent, dans le domaine de l’ultravide, une bonne maîtrise des propriétés sous vide des matériaux et de leurs traitements est de grande importance. Cette note, loin d’être exhaustive, fournit les connaissances de base du phénomène du dégazage ; elle est principalement adressée au techniciens du CERN appelés à concevoir, construire et opérer des systèmes à vide complexes comme ceux des accélérateurs de particules

Vacuum simulation of the LINAC4 H- source

The 160 MeV H- Linac4 will replace the 50 MeV proton Linac2. Linac4 H- source is the new ion source. In order to study its dynamic behaviour from the vacuum point of view, the electrical network – vacuum analogy have been used. This technique allows the evaluation of the hydrogen partial pressure profile as a function of time and position, giving important information about plasma chamber and LEBT pressures. Aiming at benchmarking the following simulations, several experimental calibration campaigns are foreseen in the near future: the H- source of Linac4 requires a pulsed injection of hydrogen to reach the typically 0.1 mbar pressure mandatory for plasma formation. First preliminary results show good agreement between the experimental and the simulated profiles

Electrical Network Analysis for Vacuum Profile of MedAustron

MedAustron is a synchrotron based hadron therapy facility for cancer treatment currently under construction in Wiener Neustadt, Austria, 40 km south-west of Vienna. Ion beams of H+3 and C4+ are generated in gaseous plasma (H2 or CO2) in an Electron Cyclotron Resonance (ECR) ion source and extracted at a kinetic energy of 8 keV=u and transformed by the Low-Energy Beam Transfer line (LEBT). The beam of ions is then accelerated up to 400 keV/u in the Linear accelerator (LINAC) and transferred via the Medium Energy Beam Transfer line (MEBT) to the synchrotron. After extraction, the beam is transferred to the treatment rooms for cancer therapy use. The quality of the dose delivered to the patient for cancer treatment is ultimately determined by the performance of the beam delivery chain. The performance of beam delivery chain are accordingly influenced by many factors in the entire accelerator chain and the vacuum performance is one of key factors steering the beam quality, especially in the synchrotron. In this report, a summary of the simulations done for the entire MedAustron accelerator complex is presented by using so-called Electrical Network Analysis (ENA)