In the ion accumulation experiment aimed at linking the atomic mass unit up with the kilogram, a new ion source has been implemented to generate a bismuth ion beam and accumu-late the bismuth ions. It had turned out that the ion source for gold ions so far used did not serve to generate a sufficiently high ion current. The oven version of the new CHORDIS plasma ion source now for the first time allowed bismuth ion beams of approx. 5 mA to be generated. As an example, Figure 1 shows the ion current and the oven temperature as a function of time. At present, the source is working with a one-hole extraction system. Later, it shall be possible to generate even higher ion currents with a two-hole or seven-hole system. The oven could be used in continuous operation for 5 to 6 hours. About 10 days are required to accumulate 10 g of bismuth with an ion current of 5 mA. For maintenance work, for exam-ple on the ion source, accumulation may also be interrupted, part of the vacuum apparatus permanently remaining under vacuum. It is planned to reduce in 2005 the relative uncertainty of 1.5 % so far achieved for the determination of the mass of a gold atom [1] down to 0.04 % for the mass of a bismuth atom.