The klystron RF systems for the indiana university lens accelerator
This paper describes the Klystron RF systems for the Indiana University Low Energy Neutron Source (LENS) accelerator 425 MHz radiofrequency quadrupole (RFQ) and drift tube linac (DTL) systems. Of interest in the power conditioning system is the design of the totem-pole grid-catch modulator for the mod-anode klystrons. This topology provides a fast rise and fall and closed loop regulation for the klystron mod-anode to cathode voltage, which minimizes RF amplitude and phase droop while maximizing efficiency. Another advantage is that short pulse high rep-rate operation is viable within the average power capabilities of the klystron. The 425 MHz, 1.25 MW klystron amplifier chain will also be detailed. Of final interest, is the digital low level RF system. This provides vector control of the cavity field using direct conversion, non-I/Q sampling architecture, at a sampling rate of 132 MHz with a 12-bit analog-to-digital converter (ADC). Four input and two output channels are integrated into a 6 unit (6U) VME module, with all DSP functions performed in Xilinx Spartan-3 field-programmable gate arrays. The design and implementation of these systems, coupled with LENS operational results, will be presented.
ELECTRICAL DESIGN AND OPERATION OF A TWO-KLYSTRON RF STATION FOR THE LOS ALAMOS NATIONAL LABORATORY'
This paper presents the electrical design and operational results of the Los Alamos National Laboratory’s first 3-MW, 850-MHz RF station, which will be used as the prime RF power source for the drift tube linac tanks of the Neutral Particle Beam Ground Test Accelerator. Each station’s major components consist of (1) the two klystrons, modulator deck, and oil tank; (2) the control rack, with equipment such as AC power switching, industrial control computer and I/Os, fast protect electronics, and solenoid supplies; and (3) the high-voltage power supply, capacitor bank, and electronic crowbar protection system. The greatest detail will provided for those systems directly related to the high-voltage switching and protection networks of the klystrons. The klystrons, Thomson TH2138s, are 1.5-MW peak, long-pulse (2 ms), 6% duty, modulating anode tubes which typically operate at 85 kV and 28 A beam. The modulating anodes are parallel connected to the pulse deck, which uses the Litton L-5012 hollow-beam switch tube. The modulator deck is of unique design, using a pulse deck within a pulse deck, with discontinuous feedback to the internal deck. In this manner the deck can switch quickly, yet regulate the modulating anode voltage to an externally set, adjustable reference. The circuit also provides amplitude tracking and self protection. The RF amplitude from the klystron is flattopped throughout the pulse by the mod-anode voltage tracking the cathode voltage. The electronic components of the klystron HV protection system consist of the fault-logic hardware, which is fiber-optically coupled to the spark-gap crowbar trigger circuitry. The trigger gap is an atmospherically vented mid-plane gap, with an inductively isolated “opposite” electrode. The design of this crowbar system ensures “zero voltage” or “infinite voltage range” triggering. Gap geometry, trigger polarity, and inductive isolation of the opposite electrode permit simultaneous breakdown b’etween electrodes, regardless of operational voltage.
Nonenzymatically galactosylated serum albumin in a galactosemic infant.
Galactosemia is a molecular disease of genetic origin that is characterized by a deficiency of galactose-1-phosphate uridyltransferase.1 , 2 The resulting severe impairment of galactose metabolism ...