 A major advance came in the 1950s, when Varian Associates were researching improvements for the performance of vacuum tubes, particularly on improving the vacuum inside the klystron.In 1957, Lewis D Hall, John C Helmer, and Robert L Jepsen filed a patent for a significantly improved pump, one of the earliest pumps that could get a vacuum chamber to ultra-high vacuum pressures.The basic element of the common ion pump is a Penning trap.