[en] The reconstruction of the Radiological Research Accelerator Facility (RARAF) at the Nevis Laboratory of Columbia University is nearing completion. In a previous report the early part of the construction of the RARAF building within the Nevis cyclotron building was described. This year we describe the completion of the building, the RARAF staff, assembly of the 4 MV Van de Graaff accelerator, and the first phase of its operation. 2 references

[en] The up-grading transformation of the Saclay FN-Tandem asked for the replacement of the aluminum electrode accelerating tube by a new one with stainless steel electrodes, and the old (yellow) resistors of the column by a set of new (blue) resistors. The first problem to be faced with was the behavior of the vacuum conditions as a function of time. A second one was due to the instability that appeared at voltages higher than 6.5 volts. This instability problem was overcome by replacing the whole set of resistors by the set of old ones

[en] Short communication. 1 ref.; 1 tab

No abstract available

[en] Principle and description of the 9 MV tandem, 1 MV Van de Graaff and connected physics installations at Saclay are given

[en] The characteristics and performance of accelerator tubes required by the new generation of large tandem accelerators and by the upgrading of existing machines are summarized. Recent experiments on surface flashover of insulators in vacuum and on the control of surface charging are briefly reviewed current theories of the microdischarge process are examined and their relevance to the operation of UHV and conventional tubes is discussed. The role of microparticles, the evidence for their existence and their influence on breakdown is reported in the light of recent experiments using laser scattering and electron microscopy. Finally, current practice and achievements are compared with the data presented by Cranberg in 1952 and some conclusions are drawn about future progress and developments

[en] In the following description we report our operational experience with a new type of belt and some developments with the charge system for the belt. (orig.)

[en] A new material called Poly-C is recommended for carrying positive charge to the terminal of a Van de Graaff accelerator. Compared to the rubberized cotton belt, the new belt gives superior performance in every way at a much lower cost. The Poly-C can be purchased as a flat sheet and joined into a continuous loop after it has been inserted into the machine. (orig.)

No abstract available

[en] The present work is mainly concerned with the high-voltage generation in a 1.5MV tandem Van de Graaff which is being built in our laboratory as a charged-particle accelerator for various nuclear engineering experiments. Maximum voltage of 1.2MV at the high-voltage terminal is measured by a generating voltmeter when the vessel is pressurized up to 7 atm with dry air. Equipotential plates, supporting columns, dehumidifer, and pellet chains have been improved for the long-term stable operation and the low costs of construction and maintenance. (Author)