**4. Development of automatic** *J***x***B* **arc-jet producer**

To produce SWNTs and carbon nanoclusters at a commercial scale by the *J*x*B* arc-jet dis‐ charge method, a revolver-injection-type arc jet producer (RIT-AJP) has been developed by collaboration with Daiavac Ltd. (Japan) [9].

A schematic and photograph of RIT-AJP are shown in Fig. 16. The left side of the machine is an arc discharge chamber, which consists of a vacuum vessel made of stainless steel 25 cm in diameter and 70 cm high that is uniformly cooled by water jackets. About 5 L of water is stored in the jackets and cooling water is slowly supplied to the jackets. In the central part of the chamber, a cathode electrode (30 mm in diameter), an anode electrode, an exhaust port, a viewing port and an electrode-cleaning hand are mounted. The top and bottom parts of the chamber are soot collectors, with an inner diameter of about 25 cm and a height of 24 cm, in which produced soot is deposited. Using these collectors, as much as 25 L of soot can be easily collected after a single operation.

The right side of the apparatus is a revolver-type carbon rod magazine. In the cylindrical metal vacuum vessel, which is 34 cm in diameter and 49 cm long, there is a rotatable cylin‐ drical magazine, in which as many as 50 carbon rods of 6 - 10 mm diameter and 300 mm length can be loaded. A schematic figure of the material-feeding mechanism of the magazine is shown in Fig. 17(a), and a photograph of a rotatable carbon rod magazine (for 50 carbon rods) is shown in Fig. 17(b). Under the vacuum chamber, there is a vacuum pump, an elec‐ trical controller and a microcomputer. Discharge power is supplied by an inverter-type DC power supply (Daihen Co., ARGO-300P).

The production sequence is as follows. First, up to 50 carbon rods are loaded in the maga‐ zine, and the chamber is evacuated by the vacuum pump. After evacuation to a pressure of less than 10 Pa, pure helium gas is introduced and the chamber is closed. Upon turning on the electrical controller, a metal striker pushes one of the carbon rods towards the cathode, and the discharge starts upon electrical contact. As the discharge conditions are determined by the discharge voltage and discharge current, the carbon rod is automatically moved until both parameters match the set values. Once the carbon rod is consumed, the cylindrical car‐ bon magazine rotates 1/50 of a turn and the next carbon rod is inserted by the striker. A magnetic field can be applied by a block-type ferrite magnet located outside the chamber, by which a magnetic field of about 2 mT is applied horizontally to the discharge space. Carbon deposited on the cathode is removed by a cathode-cleaning hand. After the discharge, pro‐ duced soot that has been deposited is carefully collected.

As an example of the continuous production of carbon clusters, fullerenes are produced. Us‐ ing 134 carbon rods of 8 mm diameter, continuous *J*x*B* arc-jet discharge is carried out, where *p*(He)= 40 kPa, the discharge current is *I <sup>d</sup>*= 120 A, the voltage between electrodes is *V rod*~ 33 V and the gap distance is *d <sup>G</sup>*~ 5 mm. The insertion speed of the carbon rods is about 30 cm/h. After the discharge, carbon soot from three parts (the top collector, central chamber and bottom collector) is collected separately and their masses are measured. The amount of soot deposited on the top wall is considerably increased by applying the magnetic field, be‐ cause the carbon molecules are blown upward onto the top wall. After sufficient mixing, the C60 content in the soot is measured by a UV/visible spectrometer (Shimadzu Co. UV-1200). At the top collector, the C60 content is the highest and about 14 W% of C60 is present, where‐ as, 4.2 W% is present on the center wall and 2.9 W% is present on the bottom wall. In total, about 105 g of soot containing about 7 g of C60 is produced in 12 h.

The contents of higher fullerenes in the soot are measured using a high-pressure liquid chro‐ matograph (HPLC) (Jasco Co., Gulliver Series, PU980) [27]. The collection rates of C60, C70, C76, C78 and C84 for two different magnetic fields are shown in Fig. 18. White rectangules in the graphs show the measurement errors. By applying a magnetic field, the collection rates of these fullerenes considerably increase.

**Figure 18.** Collection rates of C60 and C70 (a), and C76, C78 and C84 (b) for two different magnetic fields.

#### **5. Summary**

Cobalt-encapsulated carbon nanoparticles, which also have ferromagnetic properties, are produced by the arc-jet discharge method. They are dispersed in pure water with a small amount of surfactant (gelatin *etc*.) and mixed using a supersonic homogenizer (Sonic Co., VX-130) for 1 h. Finally, a black inklike liquid is obtained. The dispersion is homogeneous and stable, and most of the particles do not precipitate even after one month. These watersoluble magnetic nanoparticles potentially have many applications in the fields of liquid sealing, medical diagnostics and medical treatment [26]. Figure 15 shows a photograph of

To produce SWNTs and carbon nanoclusters at a commercial scale by the *J*x*B* arc-jet dis‐ charge method, a revolver-injection-type arc jet producer (RIT-AJP) has been developed by

A schematic and photograph of RIT-AJP are shown in Fig. 16. The left side of the machine is an arc discharge chamber, which consists of a vacuum vessel made of stainless steel 25 cm in diameter and 70 cm high that is uniformly cooled by water jackets. About 5 L of water is stored in the jackets and cooling water is slowly supplied to the jackets. In the central part of the chamber, a cathode electrode (30 mm in diameter), an anode electrode, an exhaust port, a viewing port and an electrode-cleaning hand are mounted. The top and bottom parts of the chamber are soot collectors, with an inner diameter of about 25 cm and a height of 24 cm, in which produced soot is deposited. Using these collectors, as much as 25 L of soot can

The right side of the apparatus is a revolver-type carbon rod magazine. In the cylindrical metal vacuum vessel, which is 34 cm in diameter and 49 cm long, there is a rotatable cylin‐ drical magazine, in which as many as 50 carbon rods of 6 - 10 mm diameter and 300 mm length can be loaded. A schematic figure of the material-feeding mechanism of the magazine is shown in Fig. 17(a), and a photograph of a rotatable carbon rod magazine (for 50 carbon rods) is shown in Fig. 17(b). Under the vacuum chamber, there is a vacuum pump, an elec‐ trical controller and a microcomputer. Discharge power is supplied by an inverter-type DC

The production sequence is as follows. First, up to 50 carbon rods are loaded in the maga‐ zine, and the chamber is evacuated by the vacuum pump. After evacuation to a pressure of less than 10 Pa, pure helium gas is introduced and the chamber is closed. Upon turning on the electrical controller, a metal striker pushes one of the carbon rods towards the cathode, and the discharge starts upon electrical contact. As the discharge conditions are determined by the discharge voltage and discharge current, the carbon rod is automatically moved until both parameters match the set values. Once the carbon rod is consumed, the cylindrical car‐ bon magazine rotates 1/50 of a turn and the next carbon rod is inserted by the striker. A magnetic field can be applied by a block-type ferrite magnet located outside the chamber, by which a magnetic field of about 2 mT is applied horizontally to the discharge space. Carbon

the stable iron-containing carbon nanoparticles dispersed in water.

**4. Development of automatic** *J***x***B* **arc-jet producer**

14 Syntheses and Applications of Carbon Nanotubes and Their Composites

collaboration with Daiavac Ltd. (Japan) [9].

be easily collected after a single operation.

power supply (Daihen Co., ARGO-300P).


**3.** By increasing the magnetic field, the production rate of carbon soot including SWNTs considerably increases, in which the quality of the SWNTs remains high. Water-soluble SWNTs can be obtained by additional processing.

[6] Journet, C., Maser, W. K., Bernier, P., Loiseau, A. Lamy de la Chapele, M., Lefrant, S., Deniard, P., Lee, R., Fischer, J. E., Large-scale production of single-walled carbon

Production of Carbon Nanotubes and Carbon Nanoclusters by the JxB Arc-Jet Discharge Method

http://dx.doi.org/10.5772/51964

17

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