| PLEASE - TAKE A MOMENT TO READ SECTION ONE [1] BEFORE PROCEEDING TO INSTALLATION GENERAL DESCRIPTION - SPI PLASMA-PREP II? | |
| 1-1 | GENERAL COMMENTS |
| The SPI Supplies Plasma-Prep II is a table top plasma chemistry reactor designed to provide plasma technology at a moderate cost. This simple-to-operate instrument can perform repeatable plasma chemical reactions with a minimum of automation. All controls are manual; however, where necessary, automatic monitors and controls take over to protect the equipment and the samples in the reactor. The Plasma-Prep II comes equipped with an internally housed RF generator. RF power is transferred from a power amplifier directly coupled to the reaction chamber. A variable capacitor provides a tuning control for resonating the power amplifier. An audible alarm sounds whenever the power amplifier is out of resonance. This also aids in tuning since the alarm-off "window" corresponds to the "in tune" state of the machine. Instrumentation for the Plasma-Prep II consists of a power tuning indicator and the audible tuning alarm. | |
| 1-2 | FUNCTIONAL DESCRIPTION |
| The Plasma-Prep II is a small reactor which weighs under 31 pounds fully assembled, less vacuum pump. With the exception of the external vacuum pump, it is a fully self-contained machine. It consists of an RF generator and associated tuning circuits, a vacuum system with solenoid control valves, a constant feed gas supply system and a reaction chamber system which includes two semitubular electrodes and two Pyrex glass chamber elements. | |
| 1-2.1 | |
| RF Generator - The RF power source includes a solid state oscillator operating at 13.56 MHz, the FCC-authorized industrial frequency. A solid state driver and two 4-65A vacuum tube power amplifiers operated in parallel to conservatively provide a continuous wave power of 100 watts. Power transfer to the reaction chamber is accomplished via the electric field between the semitubular electrodes. Maximum power transfer is realized by a suitable tap on the final amplifier tuned circuit. The tuning control allows the tuning of the final amplifier tuned circuit to resonance providing the maximum output power. | |
| 1-2.2 | |
| Vacuum System - The vacuum system includes the vacuum pump (not supplied as part of the Plasma-Prep II), the vacuum hose, the vacuum valves and the control circuitry. The vacuum valve switch is interlocked with the RF generator switch to prevent the RF power from coming on unless the vacuum valve is energized. (CAUTION: There is no vacuum sensing, so the vacuum pump must be attached and operating). | |
| 1-2.3 | |
| Gas Supply System - The gas supply system for the Plasma-Prep II consists of the gas delivery system inside the reaction chamber. This delivery system is a glass tube sealed on the inner end and perforated along its bottom surface. Connections to the delivery tube are made by sliding the silicone tubing over the barbed fittings on the glass chamber. | |
| 1-2.4 | |
| Reaction Chamber - The reaction chamber sub-system consists of an upper and lower electrode and a two element Pyrex glass reaction chamber (See Fig. 2-1). (For CF4 operation, a quartz chamber should be used). These are open ended cylinders designed to fit into each other to form a closed chamber. The chamber is sealed with a flat silicone gasket which seats against a raised lip on the inner chamber portion. The gas delivery tube feeds through the back of the outer chamber section. This chamber section also provides connection to the vacuum hose by a glass tube joined at the front of the chamber. The inner chamber is perforated by a series of slots located on the bottom surface of the chamber. Four little glass "feet" on the bottom of the inside chamber raise it off the inside surface of the outer chamber to provide a space between the two chamber sections. This arrangement provides for the best gas conduction flow and results in repeatable, dependable processing. | |
| 1-2.5 | |
| The AAS (Audio Alarm System) is provided to give an alarm when the plate dissipation of the final amplifier is excessive. Simultaneously, the AAS will disable the RF drive to the final amplifier and reduce this plate dissipation. This sets up a cyclical or pulsed mode. In this mode the RF power is turned on and off on a duty cycle that is inversely proportional to the plate dissipation. That is, the greater the dissipation, the shorter is the time the power is on. This will effectively protect the final amplifier tube's life, as excessive plate dissipation shortens tube life. | |
| 1-3 | SAFETY INFORMATION |
| Interlocks - There are two microswitch interlocks engineered into the machine to prevent injury to operating personnel. These are: | |
| a. | Front door interlock-cuts off AC to the RF power supply |
| b. | Right side, front and rear-shuts off all primary power |
| ***WARNING*** | |
| SINCE THE GAS MOST USUALLY USED IN THE PLASMA-PREP II IS OXYGEN, NO SMOKING SIGNS SHOULD BE POSTED NEAR THE MACHINE AND THE NO SMOKING BAN OBSERVED | |
| Even if a different gas is going to be used, we still recommend the enforcement of the NO SMOKING ban because, quite frequently, the user has an unanticipated need for oxygen and the NO SMOKING ban would be appropriate. | |
| 1-4 | TYPICAL PLASMA PROCESS |
| The "Plasma Process" is accomplished through the use of a low pressure, RF induced gaseous discharge. The material or specimen is loaded into the reaction chamber. The chamber is evacuated to a mild vacuum (approximately 200 microns) by a mechanical vacuum pump. A carrier gas is drawn through the chamber over the specimen. Radio frequency power is applied around the chamber (at 13.56MHz). This excites the carrier gas molecules and changes some of them into chemically active atoms and molecules. The mechanism employed in this process is one of oxidation. Electrons produced by ionization of gas, gain energy in the electric field. Subsequent collisions between these energetic electrons and neutral gas molecules result in an energy transfer to the molecules producing chemically active atoms, free radicals, ions and free electrons. The combustion products, which are completely dissociated and harmless, are carried away in the gas stream. The unique property of this process is that it occurs near ambient temperatures without employing toxic chemicals. | |
| 1-5 | ACCESS TO PROCESS MONITORING |
| Another connection is provided for the addition of a pressure transducer to monitor chamber pressure. Recommended Model #11019 (see page 10). This connection is marked PRESS (Pressure) PORT. Spare parts are available (see page 25). TABLE OF SPECIFICATIONS | |
| PHYSICAL DIMENSIONS | |
| Height | 10.5 inches (26.7cm) |
| Width | 11.8 inches (30.0cm) |
| Length | 14.8 inches (37.6cm) |
| WEIGHT | |
| Assembled | 31 pounds |
| Ship w/container | 44 pounds |
| EFFECTIVE CHAMBER SIZE | |
| Inside length 5.9 inches (15.0cm) | |
| Inside diameter 4.15 inches (10.54cm) | |
| RF POWER | 0 to 100 Watts |
| RF FREQUENCY | 13.56MHz crystal controlled |
| RF TUNING | Variable capacitor to maintain resonance |
| AC POWER | 120 VAC, 50/60Hz 15 amp line service (not including vacuum pump) |
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