under construction


Solid hydrogen powder injection INTO tokamak PLASMAS

The work is a part of the program Dust in high temperature plasmas supported by Russian Ministry of Atomic Energy, contract #, August, 20, 2004.

Powder material

H2, D2

Powder volume in one pulse

1 mm3

Powder velocity

1 km/s

Jet diameter

0.1 mm

Accelerating technique

Extrusion caused by mechanical shock

Power production

In-situ freezing inside the copper microcapsules

2 MHz ultrasonic fountain atomizer producing finely dispersed aluminum powder

Finely dispersed aluminum powder (spherical, particle size 1-3 microns) is used as a pigment filling for polymeric composite materials, as a part of corrosion preventing and lithographic paints and as a base of various explosives, pyrotechnic, lightning and welding compounds.

Finely dispersed powders with a large surface of the particles produce the paints with a better adhesion and protective properties. The oxidation processes of such a powder are much faster. At present the powder with a wide particle size distribution is produced and then selected to obtain finely dispersed fraction. The project assumes direct production of finely dispersed aluminum powder in an ultrasonic fountain.

Well known technique of liquid atomization in ultrasonic fountain has been improved and applied to high temperature liquids and melts at 600-700C. A conical stainless steel ultrasonic concentrator (pos. 6 in the figure below) separates water cooled piezoelectric elements (pos. 20) from the atomized liquid. The device was successfully tested and provided 1 3 cm3 of NaOH powder per minute at the power consumption of 400 W and melt temperature of 600-650C.

The technique is currently being extended for Aluminum powder production at700-800C (Al melting point - 660C)




Working pressure

10 mTorr 1 Torr

Base pressure

0.5 mTorr

Working RF generator frequency

13.56 MHz

Power input into plasma

50 W-1 kW

Working gases

Ar, N2, O2

Gas flow

up to 10 sccm

The source includes the following parts:

  • RF generator, working frequency 13.56 MHz, maximal output power of 1000 W (Generator 1).

  • RF generator, working frequency 13.56 MHz, with pulse-amplitude modulation (PAM) of the output power with maximal output power of 500 W (Generator 2).

  • L-type matching box with two tunable capacitors.

  • Plasma chamber made of cylindrical quartz tube supported by stainless steel flanges.

  • Helical inductive coil installed on the plasma chamber.

  • The processing chamber (300 mm inner diameter, 80 mm height) with special flanges designed for insertion a Langmuir probe to measure plasma parameters distribution within the plasma volume.

  • Retarding field energy analyzer for measuring ion energy distribution functions on the substrate plane.

  • Vacuum pumps and evacuating pipes providing the above said working and base pressures.

  • Appropriate Langmuir probe set with data acquisition system.

The test device will be tested to determine the following:

  • Possibility of ignition of inductively coupled plasma at various conditions (gas pressures, gas compositions, input power levels, coil geometry).

  • Radial distributions of plasma density and temperature (estimated from Langmuir probe measurements data) measured at two plasma cross-sections (one in the upper part of the processing chamber, 0-2 cm from the plasma chamber and another in the lower part of the processing chamber, 1-2 cm from the bottom) at various conditions (see above).

  • Ions energy distribution functions on substrate plane (80 mm apart of the plasma chamber cross-section) preferably measured at several points along the substrate plane radius.

The main goal of the experiments is to find appropriate operating conditions (coil configuration, RF matching conditions, gas pressure, RF power input, gas flow etc) allowing to achieve dense (density > 1011cm-3) and uniform (uniformity < 10%) plasma within a wide area (Æ > 10 cm).

The supplementary goal of the experiments is to investigate an effect of pulsing plasma ignition on the averaged plasma parameters.

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