Examination of the plasma located in PSI Ring Cyclotron

Abstract

A plasma has been observed inside the vacuum chamber of the PSI Ring Cyclotron. This ionized gas cloud maybe a substantial contributor to several interior components having reduced lifetimes. The plasma's generation has been directly linked to the voltage that is applied to the Flat Top Cavity through visual confirmation using CCD cameras. A spectrometer was used to correlate the plasma's intensity and ignition to the Flat Top Cavity voltage as well as to determine the composition of the plasma. This paper reports on the analysis of the plasma using spectroscopy. The spectrometer data was analyzed to determine the composition of the plasma and that the plasma intensity (luminosity) directly corresponds to the Flat Top voltage. The results showed that the plasma was comprised of elements consistent with the cyclotrons vacuum interior.

Analysis and suppression of RF radiation from the PSI 590 MeV cyclotron Flat Top Cavity

“…As a result one would have to exactly know the position of the lips in order to take into account the vacuum chamber acceleration effect. Figure 9 shows the power inserted into the real life FTC and the correspond-ing voltage [4]. The comparison point between this study and the measured data is at 500 kV.…”

“…The fine placement of the lips will be shown to be the dominant term in the amount of power leaking out of the cavity in to the vacuum space. In turn, the leaked power is igniting a plasma and creating secondary emission of particles in various regions in the cyclotron vacuum space [4]. Through these studies it is hoped to identify the tolerance needed to minimize leaked power and identify methods to improve the existing cavity, as well as establish criteria needed for future cyclotron cavities.…”

“…ure 8 shows the "realistic case" model and the line integration used to determine Figure 9 shows the power inserted into the real life FTC and the correspond-ing voltage [4]. The comparison point between this study and the measured data is at 500 kV.…”

“…Lastly, though not a limitation to the cavity itself, a plasma is being generated by the FTC within the vacuum space located within the sector magnets. This plasma may be causing the metal deposition observed on the critical ceramic components as well as coupling power out of the cavity [4].…”