STUDIES OF ENERGY RECOVERY LINACS AT ... - CASA

TABLE 5.1: Comparison of simulation predictions, experimental results and the analytic
calculation of the threshold current.
Method Threshold Current (mA)
Simulation TDBBU 2.1
MATBBU 2.1
ERLBBU 2.1
BI 2.1
Experimental Direct Observation 2.3 ± 0.2
Kicker-based BTF 2.3 ± 0.1
Cavity-based BTF 2.4 ± 0.1
Growth Rates 2.3 ± 0.2
(method 1) 2.3 ± 0.1
2.3 ± 0.1
(method 2) 2.2 ± 0.2
Analytic Analytic Formula 2.1
in different current regimes (above and below the threshold) and working in both
the time and frequency domain, there is complete agreement in determining the
threshold current.
To emphasize the value of the single mode threshold current derived in Sec-
tion 4.2, Table 5.1 includes the threshold current as determined by plugging values
for the 2106 MHz mode in Eq. (4.21). The analytic formula agrees very well with
both simulations and experimental data.
The results summarized in Table 5.1 represent the first time BBU simulation
codes have been benchmarked with experimental data. The measured data and the
simulation predictions agree to within 10%. As a consequence of benchmarking the
codes, the validity of the analytic model used to describe BBU, and the threshold
current formula in particular, have been confirmed.
137