If the battery tube will take modern batteries, such as C or D dry cells, AND there is no capacitor, it will probably fire just fine on 3 volts.
Many simple American flash guns of the 1930's - '60's would use two 1.5 volt dry-cells.
How does it connect to the camera ? PC coaxial connection, or a cable release with sync on the flash-gun ?
Booklet shows flash attached to a 6x6 ancestor of the Ikonta.