No abstract

ELECTRON BEAM EXTRACTION ON PLASMA CATHODE ELECTRON SOURCES SYSTEM. The electron beam extraction through window of Plasma Generator Chamber (PGC) for Pulsed Electron Irradiator (PEI) device and simulation of plasma potential has been studied. Plasma electron beam is extracted to acceleration region for enlarging their power by the external accelerating high voltage (Vext) and then it is passed foil window of the PEI for being irradiated to any target (atmospheric pressure). Electron beam extraction from plasma surface must be able to overcome potential barrier at the extraction window region which is shown by estimate simulation (Opera program) based on data of plasma surface potential of 150 V with Ueks values are varied by 150 kV, 175 kV and 200 kV respectively. PGC is made of 304 stainless steel with cylindrical shape in 30 cm of diameter, 90 cm length, electrons extraction window as many as 975 holes on the area of (15 65) cm 2 with extraction hole cell in 0.3 mm of radius each other, an cylindrical shape IEP chamber is made of 304 stainless steel in 70 cm diameter and 30 cm length. The research result shown that the acquisition of electron beam extraction current depends on plasma parameters (electron density ne, temperature Te), accelerating high voltage Vext, the value of discharge parameter G, anode area Sa, electron extraction window area Se and extraction efficiency value .

The Center for Accelerator Science and Technology (CAST – BATAN) is developing a cyclotron that eventually will be used for radioisotope production. The cyclotron accelerates charged particles (?−) generated by ion source through circular trajectories up to the desired energy and form proton beams through an extraction system. In the early operational stage, the beam current strongly influenced by the flow speed of hydrogen gas in the head of an ion source, therefore the gas flow performance needs to be characterized. Evaluation have been undertaken which cover component identification, data collection and analysis of the obtained data. The operational data of the opening gas valve is represented by the voltage and flow rate. This evaluation results can be used as a basis or guidance for further construction of the ion source instrumentation control system.

No abstract

Dalam siklotron, magnet merupakan komponen utama untuk menghasilkan lintasan partikel melingkar dan memfokuskan berkas partikel. Sebuah sistem magnet siklotron dengan kapasitas 13 MeV telah berhasil dibangun. Selanjutnya karakteristiknya dievaluasi dengan membandingkan nilai isokronus magnet yang dibangun terhadap hasil simulasi. Proses tersebut dilakukan melalui tahapan komisioning dan pemetaan medan magnet (untuk mengukur distribusi medan magnet dari setiap hill magnet dengan menggunakan sensor Tesla Meter dalam interval jarak pengambilan data 5 mm selama +9 jam). Dengan menggunakan arus koil maksimum 133 A dan menggunakan 2 (dua) hall probe hasil mapping medan magnet menghasilkan kurva medan rerata di atas medan isokronus dengan rentang kesalahan 0,3%. Akan tetapi, pada jari-jari kurang dari 8 cm medan rerata masih dibawah kurva isokronous. Oleh karena itu, perlu proses shimming dengan menambah ketebalan bump 0,5 mm pada area pusat dan mengurangi medan rerata pada jari-jari lebih dari 8 cm supaya mendekati kurva isokronous.