A turbomachine rotor has a disk carrying vanes, each vane having a blade linked by a platform to a root. For at least one vane, a recess is defined between the platform and the disk, and a vibration damper is mounted in the recess. The vibration damper includes a first structural portion configured to contact the platform of which the vibrations are to be dampened, and a second mass portion configured to dampen these vibrations. The second mass portion is a powder and the first structural portion is a box containing the powder.