The history and development of the vertical injector Van de Graaff is summarized from its commissioning in 1965 to its present use as a source of intense α-particle beams of 9-10 MeV and of 40-50 MeV neon beams. The decision to convert the machine to a folded Tandem is justified in the light of the experimental programme and of the technical and economic factors involved. Some features of the folded Tandem design are discussed, the state of the conversion is reviewed and the performance goals are described.L'histoire et le développement de l'injecteur Van de Graaff vertical sont résumés depuis la réception en 1965 jusqu'a son utilisation actuelle comme source intense de faisceaux de particules α de 9-10 MeV et de néon de 40-50 MeV. La décis...