Studies of Electron Beams from a Febetron 705

The electron beams from a Febetron 705 with two modified diodes have been studied. Both diodes gave hollow cylindrical beams with more than 4 × 1013 electrons within ~3% of the maximum beam energy and within 10 ns. The conventional two-dimensional emittance for 90% of the beam was measured to be 0.13 (¿ cm rad.). The four-dimensional phase space projected into r-r¿ gives an emittance of 0.15 cm rad. Emittance values for various fractions of the beam are also given.