Monochromated X-Ray Source with XR5 Electron Gun
Issue 5
Monochromator and XR5 (HA600054)
7
Interlock
Name
Interlocked
Tripped By
Inhibit
s
Status Displayed to Operator
TWIN
cover
XR3/XR4 Twin X-
Ray source
protective cover
being removed.
Power to
source.
Interlock display in software will display
FAIL
in
RED
In addition light “
1”
LED on the rear of the power
supply will illuminate
RED
.
MONO
cover
XR5 Mono Covers
Source Protective
cover being
removed.
Power to
source.
Interlock display in software will display
FAIL
in
RED
In addition light “
2”
LED on the rear of the power
supply will illuminate
RED
.
VACUUM
Main chamber (ion
gauge) pressure
above
1x10
-6
mbar
Power to
source.
Interlock display in software will display
FAIL
in
RED
In addition light “
3”
LED on the rear of the power
supply will illuminate
RED
.
Relay A on Ion Gauge Controller (IGC) LCD
display:
LED On = Enabled
LED Off = Tripped
WATER
flow
Water flow through
the X-Ray source
(XR4 or MXR1)
drops below 2.8
l/min
Power to
source.
Interlock display in software will display
FAIL
in
RED
In addition light “
4”
LED on the rear of the power
supply will illuminate
RED
.
CABLES
Cables removed
from rear of
T352/NT power
supply
Power to
source.
Interlock display in software will display
FAIL
in
RED
In addition light
“5”
LED on the rear of the power
supply will illuminate
RED
.
Table 1: T352 Instrument Interlocks
There are additional safety features built into the T352/NT power supply that will inhibit
power to the X-ray source but will display as a “pop-up” box by the
Avantage
software,
they include:-
x
Temperature in T352 Power Supply rises to unacceptable levels.
x
Current drawn from T352 Power Supply HV greater than 60 mA.
x
Drain from HV through X-ray water lines greater than 20 mA.
Monochromated X-Ray Source with XR5 Electron Gun
Monochromator and XR5 (HA600054)
Issue 5
8
3 Description
3.1 Introduction
The Monochromated X-Ray Source produces X-Rays which have well defined energy
resolution and are micro-focussed onto the sample to give a spatially defined area of
analysis. To achieve this several distinct components are employed. Firstly there is an
electron gun, the XR5, designed to provide a high power source of focused electrons
at energies of up to 15kV. These electrons impact on the anode, in this case an
aluminium coated version, to produce X-Rays at an energy of around 1486.6eV.
The X-Rays are then diffracted by a pair of quartz crystals which are arranged such
that the angle between the crystal lattice and the X-Rays is the appropriate Bragg
angle. The diffracted X-Rays are thus monochromated to give a pure Al K
D
beam (of
much lower energy spread). The crystals are also shaped and positioned so that the
diffracted X-Rays are focussed into a well defined spot on the sample surface at the
analysis position.
The XR5 electron gun and anode voltage are controlled by a single power supply, the
T352/NT. This supply has no manual user interfaces, being controlled entirely from the
Avantage
Datasystem.
The ESCALAB 250 monochromator system consists of 5 major components:
x
XR5 Electrostatic Electron Gun
x
Monochromator Water System
x
T352/NT Digital X-ray Supply
x
Monochromator Crystal Assembly
x
Data System Monochromator Control Software.
Figure 3-1: The Monochromator Assembly
