The technical feasibility of very high power tetrodes at high frequencies for ICRH - the new developments

After earlier successful achievements in TFR (France) and Heliotron E (Japan) in ICRH applications, new requirements from physicists working in plasma heating appeared during recent years. They show a trend towards increased unit peak power operating over longer pulses at higher frequencies. The problems well known to manufacturers of gridded power tubes, which are inherent to such applications became more difficult to overcome. The present paper describes how the mastery gained on past experience by Thomson-CSF at high power and high frequency was instrumental in overcoming these difficulties through appropriate design and manufacturing processes of gridded power tubes fulfilling the most stringent ICRH requirements