[en] Cryogenic linear accelerator structures have high rf efficiency due to reduced resistivity and high heat transfer capability from the boiling heat transfer regime. Finite-element transient heat transfer and thermal stress analysis is used to simulate the behaviour of linear accelerator structures during quenching and predict their characteristics during power operation. 21 refs

[en] The rf design of a stabilized tunable high current RFQ was accomplished while remaining compatible with extreme pumping and cooling requirements. Several design innovations were introduced, including distributed pumping, compensated straps, dual dynamic balanced tuners and a tuner compensated drive loop. The code RFQ3D was demonstrated to be quantitatively useful for predicting design characteristics. (author)

[en] Reliability is of paramount importance for industrial ion-beam systems. However, manufacturing processes often involve the operation of ion sources at elevated temperatures with corrosive and erosive feeds. Under these conditions, the durability of various components, and especially cathodes, may be reduced by physical sputtering and chemical erosion. The duoPlGatron ion source, having two chambers, is well suited to minimizing this problem. The first chamber houses the cathode and serves as an electron generator for the second PIGing, or reflex arc, chamber where most of the extracted ions are created. Consequently, the first chamber can be operated on an inert gaseous feed chosen to maximize filament lifetime, while the second chamber is fed a noxious gas or vapor that gives rise to the ion of interest. This principle has already been applied to a high-current oxygen source that was developed for the Eaton NV-200 high-energy ion implanter. The technique has also been demonstrated with the gases phosphine, arsine, and boron trifluoride as secondary feeds. The present paper reports on the operation of a modified duoPlGatron with vapor genera ed by an external oven. (author)

[en] This paper reviews design challenges of normal-conducting radio-frequency (RF) cavities for B-factory applications with particular emphasis on the thermal-mechanical design of 476 MHz high average power RF cavities for the proposed PEP-II B-Factory

[en] This report describes the development of a mechanical design for a single-cell 476 MHz room-temperature rf cavity suitable for the PEP-II Asymmetric B-Factory Project at the Stanford Linear Accelerator Center. The work comprised preparation of a preliminary mechanical design of a single-cell 476 MHz rf cavity capable of handling 150 kW dissipation in the cavity walls. The results of extensive two dimensional and three dimensional heat transfer and thermal stress analyses of the cavity structure under high power operating conditions are presented, and a mechanical design and fabrication scheme is proposed. (Author) 9 refs., 38 figs., 4 tabs

[en] The Chalk River RFQ1 accelerator was built with replaceable vanes, and the design of a new set vanes was described at the 1990 Linear Accelerator Conference. The vanes have new been fabricated. They are identified as RFQ1-1250, while the original vanes are identified as RFQ1-600. The RFQ1-600 vanes were designed with a peak surface electric field of 1.5 times Kilpatrick, which is now viewed as being too conservative. The new design uses a peak field of 1.8 Kilpatrick and a modified tip profile to increase the output energy from 0.6 MeV to 1.25 MeV. Computer simulations have been done using PARMTEQ and RFQCOEF to assess the effects of higher order harmonics of the potential on beam losses. The vanes have been machined out of GlidCop reg-sign AL-15 (an alumina dispersion-strengthened copper) with the cooling channels gun drilled. Details of the fabrication, including details of the tip profile cutting, installation and tuning are described

[en] Doubling the beam power on the RFQ1-1250 linear accelerator at Chalk River and designing a 40 kW beam diagnostic system for Tokamak de Varennes required a detailed investigation into the power handling capabilities of beam stops. Different techniques for augmentation of the critical heat flux on the cooling channel surface of beam stops are reviewed. In the case of a beam stop with twisted tape inserts, the swirl flow condition yields a higher critical heat flux than that of a straight axial flow. Although a critical heat flux in the order of 10 kW/cm² could be obtained at high flow velocities such as 45 m/s, such flows are not always practical in the design of beam stop cooling systems. At a water velocity of 4 m/s, the highest beam power density is estimated to be 1.4 kW/cm² for a beam stop design that uses double rows of cooling tubes. A similar design, where cooling channels are machined on a common copper block, would handle a power density up to 2.6 kW/cm². Some preliminary hydraulic test results, related to a third design where high flow turbulence is created by two rows of intersected-channels, are also reported. (Author) 5 refs., 4 figs

[en] Thermal expansion and thermal stress induced strain cause the detuning and limit the power level of radiofrequency (rf) structures. Two-dimensional finite element modeling has been used to determine the operating power limits of coupled cavity systems, but for complex high power accelerator structures without axial symmetry, a three-dimensional analysis is necessary. This paper describes results of a three-dimensional finite element temperature and thermal stress analysis. The analysis was performed for a high power coupled cavity linac structure operating at 1350 MHz. The results of the analysis are used to determine changes in the structure rf parameters as a function of power level and cooling water velocity. (orig.)

[en] The rf design of a stabilized tunable high current RFQ was accomplished while remaining compatible with extreme pumping and cooling requirements. Several design innovations were introduced, including distributed pumping, compensated straps, dual dynamic balanced tuners and a tuner compensated drive loop. The code RFQ3D was demonstrated to be quantitatively useful for predicting design characteristics

[en] A duoPIGatron augmented by magnetic cusp confinement has been equipped with a large-volume external oven. The oven has operated at temperatures as high as 1100 degree C. Beams of lithium, phosphorus, calcium, and bismuth have been extracted with a multiple-aperture triode column at voltages of up to 40 kV. Mass normalized current densities of as much as 250 mA cm^-2 of singly charged ions have been obtained