Apart from in-cylinder pressure, there are two other signals that can be used to evaluate combustion phasing: ionization current
and engine block vibrations.
where [R.sub.x,C], [R.sub.x,A], and [R.sub.x,B] are the decay-corrected responses (ionization current
or counting rates) of the respective citrate, acid, or background source for each dilution level; [m.sub.C], and [m.sub.A] are the masses of the respective citrate and acid source; and [PI][D.sub.C,i] and [PI][D.sub.A,i] are the products of the dilution factors from that particular dilution level for the respective citrate and acid dilution chains leading to the master solution.
250[degrees]C; ionization voltage: 70eV; ionization current
: 60 [micro]A; scanning speed 1 s over 30-500 amu range; split injection system, 1:100.
Compensation is required, due to the fact that the ionization current
is proportional to not only smoke, but pressure, temperature and humidity.
The engine was also equipped with a modified ignition system that allowed the detection of the cycle resolved ionization current
without altering the ignition functions.
The air kerma calibration coefficient [N.sub.K] was determined by evaluating the ratio [N.sub.K] = [K.sub.air] / [I.sub.corr], where [K.sub.air] is the reference air kerma rate (expressed in units of Gy/s) and [I.sub.corr] is the measured ionization current
(expressed in units of C/s) corrected for influence quantities.
where [I / [[rho].sub.air]] V is the mass ionization current
measured by the standard, [W.sub.air] is the mean energy expended by an electron of charge e to produce an ion pair in dry air, [g.sub.air] is the fraction of the initial electron energy lost by bremsstrahlung production in air, and [PI] [k.sub.i] is the product of the correction factors to be applied to the standard.
Then the expected ionization current
in the WAFAC can be evaluated approximately as
I/[[rho].sub.air] V is the mass ionization current
measured by the standard,
It is therefore necessary to randomize the seeds in the re-entrant tube to determine a mean ionization current
for each seed.
I/m is the mass ionization current
as measured by the free-air ionization chamber,