Development of High Power CW and Pulsed RF Test Facility based on 1 MW, 352.2 MHz Klystron Amplifier M. K. Badapanda*, Akhilesh Tripathi*, Rinki Upadhyay, J. N. Rao, Ashish Tiwari, Akhilesh Jain, M. R. Lad and P. R. Hannurkar RF Systems Division, Raja Ramanna Centre for Advanced Technology, Indore, M.P- 452013, India Abstract A high power 1 MW, 352.2 MHz RF Test facility having CW and Pulse capability is being developed at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore for performance evaluation of various RF components, accelerating structures and related subsystems. Thales make 1 MW, 352.2 MHz klystron amplifier (TH 2089) will be employed in this high power test facility, which is thoroughly tested for its performance parameters at rated operating conditions. Auxiliary power supplies like filament, electromagnet, ion pump and mod anode power supply as well as 200 W solid state driver amplifier necessary for this high power test facility have been developed. A high voltage floating platform is created for floating filament and mod anode power supplies. Interconnection of various power supplies and other subsystems of this test facility are being carried out. A high voltage 100 kV, 25 Amp DC crowbar less power supply and low conductivity water (LCW) plant required for this klystron amplifier are in advanced stage of development. NI make cRIO 9081 real time (RT) controller based control and interlock system has been developed to realize proper sequence of operation of various power supplies and to monitor the status of crucial parameters in this test facility. This RF test facility will provide confidence for development of RF System of future accelerators like SNS and ADSS. INTRODUCTION A 1 MW, 352.2 MHz, RF test stand based on Thales make TH 2089 klystron amplifier is being developed at RRCAT, Indore for characterization and qualification of RF components, cavities and related subsystems. Complete 1 MW RF system is shown in Figure 1. A klystron amplifier is a sensitive device and its life depends on how stored energies are taken care of, during internal flashover, arcing, etc., since its arc resistances reduce to very low value during arcing. Some klystron manufacturers keep restriction on allowable fusing action of the arc current, i.e, a limit on the maximum I 2 t, while others keep restriction on the maximum allowable energy that can be allowed to pass through these arcing klystrons [1]. The TH 2089 klystron amplifier employed in this system, can tolerate about 20 Joules of energies called „critical energy under arcing‟ and about 40 A 2 Sec of fusing action called „critical fusing action under arcing‟ beyond which irreparable damage may occur. A crowbar Figure 1: Block diagram of 1 MW RF system less solid state modular 100 kV, 25 Amp DC power supply is developed and is used as the bias power supply of this klystron amplifier. The stored energy in this power supply is less than 20 Joule, which is not detrimental to this klystron amplifier during its arcing. The 100 kV DC power supply has the inherent pulse capability which can be utilized to operate this test stand in pulsed mode also. The control system is designed and developed for controlling the sequence of operation of various power supplies employed for the proper operation of this high power klystron amplifier. It also controls and monitors cooling water temperature, pressure and flow, oil temperature, cooling air flow and other environment conditions. HIGH POWER TESTING OF TH 2089 KLYSTRON AMPLIFIER TH 2089 klystron amplifier is tested for its performance evolution under rated operating conditions. Various tests like measurement of RF gain, measurement of variation of RF phase over beam voltage and beam current, measurement of output power variation against beam voltage and beam current and output power variation against mod anode voltage have been performed. These tests are carried out at central operating frequency of 352.2 MHz. Variation of RF gain with RF input power This test is conducted for determining the gain characteristics of this klystron amplifier. The variation of output power and RF gain against the input power is shown in Figure 2 and Figure 3 respectively. It is clear that RF output power initially increases, goes into saturation and then beyond saturation, it decreases with increasing input power. _______________________________________________________________ *Primary Authors E-mail: M. K. Badapanda: mkp@rrcat.gov.in Akhilesh Tripathi: atripathi@rrcat.gov.on