H uacci

V m where v is the final velocity of the particle, Uacc the acceleration voltage, q and m the particles charge and mass. An acceleration voltage of 20 kV results to a final velocity that is 1/10 of the velocity with Uacc = 2 MV.

Dust

Dust

Figure 2. The function principle of the dust source. The needle is on a fixed potential while the potential of the dust reservoir is pulsed. Particles that hit the tip of the needle are extracted to the acceleration section (on the left side, not shown).

850 mm behind the dust source, a 100 mm long shielded influence tube with a TEN-NELEC TC 16ID charge sensitive amplifier is located. Here, the flight time and charge of passing particles can be measured. The velocity of the particle is antiproportional to its flighttime. A conversion of equation (1) provides the particles mass. From a known density and the assumption of spherical particles (SEM-pictures support this assumption) one obtains the particle radius.

The first measurements at the test bench with several materials showed encouraging results. The tests were made with the following dust materials: Iron, carbon, copper, silver and latex spheres coated with a conductive layer [9]. All data were acquired with a needle potential of 20 kV, a repetition rate of 10 Hz and a pulse duration of 10 fis. The pulse amplitude was varied for each material. For the data in Table 2 100 particles of each material were selected.

JOMOhm

Extraction Pubcr Platc Unit

JOMOhm

Extraction Pubcr Platc Unit

Table 1

Properties of the new dust source.

Table 1

Properties of the new dust source.

Parameter

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