Complex sentence: During 1964, Alexander P. de Seversky had in fact published a lot of his related work in, and with the aim to forestall any possible misunderstanding about these devices, had termed these flying machines as ionocrafts.
Split into simpler sentences: During 1964, Alexander P. de Seversky had in fact published a lot of his own work in. To forestall any possible misunderstanding about his devices, he termed these flying machines as ionocrafts.