1014 Chinese Physics C(HEP NP) quality factors(Q), and R/Q values, etc. Calcula- 3 Calculation and experiment tions including its on-axis field distribution, R/Q, etc, 3. 1 1.5 GHz single cell higher harmonic were performed using MAFIA before measurements cavity In Fig. 3, the longitudinal monopole modes are calculated by MAFIA, CLANS, etc. The comparison We have investigated the high order modes up to of calculation and experiment shows that most modes Hz in the cavity and measured their frequencies, can be identified, as shown in Fig 3 E(norm)-tmOl 06 0.5 1.5 E(norm)-tm05 E(norm)-tmo6 0 0 0.2 0.15-0050.050.15 z/mm(×10) -1.0 0.15-0.050.050.15 (x102) z/mm Fig. 3. Electric fields distribution of the monopole modes in the single cell 1.5 GHz higher harmonic cavity A 0.4 2哥 4 E03(norm)-disk 0.8 04 0.4 E04(norm)-disk 2-s E05(norm)-disk (×10) Fig. 4. The lowest two dipole modes of the sing cell 1.5 GHz higher harmonic cavity1014 Chinese Physics C (HEP & NP) Vol. 32 3 Calculation and experiment 3.1 1.5 GHz single cell higher harmonic cavity We have investigated the high order modes up to 3 GHz in the cavity and measured their frequencies, quality factors (Q), and R/Q values, etc. Calcula￾tions including its on-axis field distribution, R/Q, etc, were performed using MAFIA before measurements. In Fig. 3, the longitudinal monopole modes are calculated by MAFIA, CLANS, etc. The comparison of calculation and experiment shows that most modes can be identified, as shown in Fig. 3. Fig. 3. Electric fields distribution of the monopole modes in the single cell 1.5 GHz higher harmonic cavity. Fig. 4. The lowest two dipole modes of the sing cell 1.5 GHz higher harmonic cavity