Helical Siberian snakes

The helical dipole is a new type of magnet element for charged particle accelerators. Helical dipoles are long dipoles twisted into a helix; one can be constructed with laminations, each lamination is rotated by some small angle with respect to the previous lamination. Siberian snakes using helical dipoles would have several advantages: the closed orbit excursions within the snake would be smaller; there would be fewer magnets required; and potentially the snake could be shorted so it would require less space in the ring. Fabrication techniques are explained. Construction problems and their solutions are reviewed