Utah-94-721002-System-Manual.pdf - 第181页
System Manual lñÑçêÇ=fåëíêìãÉåíë=mä~ëã~=qÉÅ ÜåçäçÖó== mä~ëã~ä~Ä=~åÇ=fçåÑ~Ä It is strongly recommended that the operation of all sa fety interlocks should be tested at the same time, whenever an RF or Microwave leakage te…
mä~ëã~ä~Ä=~åÇ=fçåÑ~Ä lñÑçêÇ=fåëíêìãÉåíë=mä~ëã~=qÉÅÜåçäçÖó== System Manual
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.
NK=pÅçéÉ=çÑ=íÉëíáåÖ=
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.
OK=jÉíÜçÇ=çÑ=íÉëíáåÖ=
Suitable test meters are the Narda
1
8511 for 1.7MHz to 2.1MHz, the Narda 8512 for 13.56 MHz and 27.12
MHz, and the Holaday
2
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.
1
The Narda Microwave Corporation, Plainview, New York 11803.
2
Holaday Industries Inc, 14825 Martin Drive, Eden Prairie, MN 55344.
Measurement of RF & Microwave Emissions
Issue 2: December 01 Page 2 of 4 Printed: 21-Dec-04, 13:43
System Manual lñÑçêÇ=fåëíêìãÉåíë=mä~ëã~=qÉÅÜåçäçÖó== mä~ëã~ä~Ä=~åÇ=fçåÑ~Ä
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.
PK=^ÅÅÉéí~ÄäÉ=ÉñéçëìêÉ=ëí~åÇ~êÇë=
Readings must be equal to or less than the levels shown in Table 1 at all points. Exceptions will only be
permitted in certain special circumstances. These exceptions will be clearly documented in the system
instructions. In all other situations, these standards must be strictly met.
Frequency Electric Field (E) Magnetic field (H)
V/m mW/cm
2
A/m mW/cm
2
0.1 to 1 MHz 614 16.3/f
1.7 to 2.1 MHz 614 16.3/f
13.56 MHz and 27.12 MHz 1842/f 900/f
2
16.3/f 10000/f
2
2.45 GHz f/300 f/300
Note – f is the frequency in MHz
Reference: ANSI/IEEE C95.1 maximum permissible exposure for controlled
environments.
Table 1 - Maximum permitted field strengths
QK=póëíÉã=ÇÉëáÖå=
RF and Microwave components such as RF ion sources may be purchased from Oxford Instruments Plasma
Technology and fitted to the customer's system. Such an installation requires a system designed to
prevent leakage of RF and Microwave emissions, and requires careful testing by the installer before use.
It is not possible to give a full list of necessary safety precautions, and advice should be sought from a
competent authority. However, some of the points to be considered are as follows:
(a) The system and all of its assemblies should be very well grounded (earthed), using low impedance
straps, and ensuring impedances between power supplies and the chamber of ≤ 0.1 Ohms at 25 A.
(b) Viewports should be shielded with fine conducting mesh to prevent the transmission of RF and
Microwave energy, and should be filtered to prevent the transmission of UV light.
(c) Doors and flanges should provide metal-to-metal contact. In case of doubt, and in the case of
access doors, the use of copper beryllium finger strips or wire mesh over elastomer core (e.g.
Zemrex products from Warth International
3
should be considered. Small flanges in the vacuum
system should be joined with metal clamps, not plastic.
(d) All types of electrical feedthrough and vacuum gauges, together with cables leaving them, may
need shielding.
(e) Interlocks will need to be wired into the system to ensure safe operation. These will include
interlocks with the system access door, the customer's water supply to the RF product, and the
system vacuum. The product purchased from Oxford Instruments Plasma Technology will also have
interlock switches. These interlocks must all force the disconnection of power from the RF,
Microwave and HV power supplies if they are opened. See the product manual for more details.
3
Warth International Ltd, Charlswood Road, East Grinstead, Sussex, England, RH19 2HH.
Measurement of RF & Microwave Emissions
Printed: 21-Dec-04, 13:43 Page 3 of 4 Issue 2: December 01
mä~ëã~ä~Ä=~åÇ=fçåÑ~Ä lñÑçêÇ=fåëíêìãÉåíë=mä~ëã~=qÉÅÜåçäçÖó== System Manual
NOTES:
Measurement of RF & Microwave Emissions
Issue 2: December 01 Page 4 of 4 Printed: 21-Dec-04, 13:43