Vacuum system

Principal scheme

Vacuum parameters

1 Preliminary vacuum 1*10-2 Pa

2 Melt storage 5*10-4 Pa

3 Crystal annealing 5*10-5 Pa

Mechanical pump.Construction and

principle of operation.

Two Stage Rotary Vane Vacuum Pump

3 phase engine

Inlet and outlet

Oil level

Oil removal

Gas flow in rotary pump

1, 7 –stages, 2,3 – valve, 4 – gas outlet, 5- gas channel, 6 – gas inlet

Vacuum characteristic

Diffusion pump

Structure of diffusion pump

1 – body; 2, 10 – covers; 3, 11 – washer; 4 – oil reflector; 5 – earth; 6 – vapor path; 7 – spiral way; 8 – heater;

Stage

Oil reflector

Cooling water

10-7 10-6 10-5 10-4 10-3 10-2 10-1100

101

102

103

104

105S

pee

d l

/sec

Input pressure, torr

Vacuum characteristic

Electromagnetic valve. Solenoid principle of operation.

Manual close ring

Engine

Cover

Vacuum lock. Construction and principle of operation.

Structure of lock

Vacuum meter APG. Principle of operation.

1- electric cable, 2- socket,3 – spring ring, 4-vacuum flange, 5-filter

Principle of operation Pirani

TO MEASURE VACUUM BY MEASURING HEAT CONDUCTIVITY OF GAS

Heater wire

Thermocouple

Vacuum meter WRG. Principle of operation.

WRG – combination of inverse magnetron sensor and PiraniWay of measuring is chosen automatically

Principle of operation

Dependence of ionized gas current on pressureCrossed magnetic field make longer path of ions before reach anode

+

-E H

Plant assembly

Vacuum line is fixed to the frame by

Joining crystallizer with 3 bolts Joining right angle tube with 2 bolts Vacuum devices and parts are mutually fixed with clamps and rings

To set the crystallizer on the frame and to fix it with the bolts

To join the vacuum tube to crystallizer and frame by means of the bolts

and the studs

To join the lock and diffusion pump by means of the studs

To set the side shields and to fix them with the screws

To set up vacuum devices

To set up water tube with water collector

Water collector

Pressure meter

Water collector

Water piping1-Valve2-Pressure meter3-12 –Valves of the grower parts13- Diffusion pump14-Thyristor15 – Chamber16 –Bottom17- Small cover18- Big cover19 -Rod20-Cutter21- Current lead 122- Current lead 223-34 –Thermal sensor of the elements35- Funnel

To set and fix with the bolts the column to the frame

To set and to fix the computer control board

To set the supports and to adjust them in order to provide for horizontal

orientation of the grower

Assembly of hot zone inside the crystallizer

Bottom SupportSide shield

W Tube

Checking the center of W-tube and the gap

Mo shield and W-tube

Shield to the current lead

Bottom shield

Bottom shield

Support

Bottom shieldGranules

Al2O3 loading

To put on and to fix the big cover with the nuts

Heater

Small cover

Lobe

Window

To set and to fix bus bars with the bolts

To set and fix the side shields on the frame

To set the transformer unit

To set the mechanical vacuum pump

Maintenance

Checking for vacuum seals and junctions Checking of water cooling system Checking for thermal screens and hot

zone elements wear Correction of crucible position

Safety measuresElectrical safetyThere are the following sources of electric safety:

chains of power supply of the component parts of the grower,panels and blocks with electric apparatus and electric equipment, located on the control panel, crystallizer, power cabinet.

Protection of maintenance staff against electrical shock is provided by the doors which can be opened by special key and by protective grounding.

There are grounding bolts with special marks on the doors of the power cabinet and control unit.

Danger of thermal burns.There are the following sources of thermal

burns: the heater, screens and the melt surface at monitoring of crystallization front through non-protected window, therefore after termination of technological process it is allowed to open the grower only after its complete cooling.

To protect the eye of process engineer from thermal irradiation at monitoring of seeding process it is necessary to use the light filter.