Radio Frequency (RF) Windows

The European Commission’s Joint Research Centre (JRC) located in Geel (Belgium) has the intention to purchase 4 GE-2024-10 RF-windows. The RF-windows are a critical component in the Geel Electron Linear Accelerator (GELINA) RF-system and for this, extra spare part are needed. The Geel Electron Linear Accelerator (GELINA) uses high power 2998MHz (S-band) radio frequency (RF) waves to accelerate electrons. The accelerator consists of 3 accelerating sections, and RF waves are generated by 3 klystrons, each with a dedicated modulator to modulate the power. Each klystron provides an RF output via 2 arms, which are connected to a corresponding accelerating section via a system of wave guides that transport the RF waves. The arms at the output of the klystrons can only safely operate under a constant SF6 gas pressure of 3 bars. As the accelerator itself operates under vacuum, windows are needed at some point in the wave guide system to separate the SF6-filled part from the vacuum part. These windows should be able to endure the given RF power, with a limited of RF power in the windows (insertion loss). At the same time, leak rates should be limited, on one hand to guarantee the vacuum inside the accelerator, and on the other hand to limit losses of SF6 to the environment, as this is an extremely strong greenhouse gas (GWP 23500). The RF-windows will serve as spare parts for existing RF-windows, and should therefore comply with the given material specifications, dimensions, flange specifications and cooling interfaces.