Plasmalab and Ionfab
Oxford Instruments Plasma Technology
System Manual
Measurement of RF & Microwave Emissions
Issue 2: December 01
Page 2 of 4
Printed: 5-Jun-09, 9:58
1.
Scope of testing
Systems which contain RF generators, both Ion Beam and Plasma systems will be tested for the
emission of energy prior to shipment. They will also be tested routinely every three months during
use, or as required by safety standards at the customer's site, if this is more frequent.
Systems must also be tested after maintenance, if the maintenance has involved RF shielding
components such as covers and viewports, or components in the process chamber such as
feedthroughs and vacuum gauges.
Systems with RF generators in the frequency range of 0.1 MHz to 27.12 MHz must be tested for
emissions by measuring separately both the electric (E) and magnetic (H) field strengths. Either field
can be a safety hazard, hence the need to test both.
Systems with microwave frequency generators at 2.45 GHz will only be tested for power, usually by
measuring the electric (E) field.
2.
Method of testing
Suitable test meters are the Narda
8511 for 1.7MHz to 2.1MHz, the Narda 8512 for 13.56 MHz and
27.12 MHz, and the Holaday
1501 for 2.45 GHz. Equivalent meters from other vendors are
acceptable. The test meter MUST have a current calibration certificate. Note that if an alternative
13.56 MHz meter is used, it should be able to detect the presence of 27.12 MHz as well as 13.56
MHz.
Testing must be performed on the system in its normal operating configuration, with the usual
covers and components in place. The system must be operating at maximum reasonable power, and
must be tested both in the presence and the absence of plasma.
The field strength must be measured 50 mm (2 inches) away from the system, at all points that can
be reached by hand with the probe (If parts of the system are inaccessible from the ground, a
stepladder must be used). The probes of the above meters are designed so that the correct distance
is obtained if the head of the probe is touching the system.
Particular attention must be given to viewports, doors and flanges, the automatch unit, and the whole
length of waveguides and RF power cables. If viewports are fitted with shutters, then tests must be
made with the shutter both open and shut. All cables leaving gauges and other feedthroughs in the
process chamber and the pumping system are suspect, and must be checked along their entire
length. The pumping system and any separate system racks and power box must also be checked.
It is strongly recommended that the operation of all safety interlocks should be tested at the same
time, whenever an RF or Microwave leakage test is performed.
1
The Narda Microwave Corporation, Plainview, New York 11803.
2
Holaday Industries Inc, 14825 Martin Drive, Eden Prairie, MN 55344.
WARNING
THIS APPENDIX COVERS ALL OF THE CURRENT REQUIREMENTS
FOR THE MEASUREMENT OF RADIO FREQUENCY AND MICROWAVE
EMISSIONS FOR THE OXFORD INSTRUMENTS PLASMA
TECHNOLOGY'S RANGE OF PRODUCTS. ENSURE THAT THE ENTIRE
APPENDIX IS READ AND UNDERSTOOD BY ALL INVOLVED
PERSONNEL AND THAT THE TESTS RELEVANT TO THE INSTALLED
SYSTEM ARE CARRIED OUT AT THE SPECIFIED PERIODICITY.
Summary of Contents for OpAL
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