ECE Radiometer
Status
10/98
- All parts have been machine and are ready
for test fitting
- Vacuum Window - has been vacuum tested and
is ready for installation, have one spare window.
- Measured transmission loss of SS
waveguide 1.5dB
- Measured transmission Loss of window 1.3
dB
- Measured transmission Loss of Teflon
insert 0.6 dB
- Measured total transmission loss of
waveguide & everything 3.4 dB
- F flange has been machine and welded and
the main vacuum surface is now being ground.
- 8" flange is now being machined and
welded.
- Auburn will ship mirror assembly to MIT and
the FRC will send the SS waveguide, vac. Window, and mounting
supports for final test fitting.
- (The
RF energy arrives from the optics along two paths, 234-270
& 270-306 GHz via overmoded waveguide. Each is shifted down
to 4-40 GHz by a single block conversion in the first down
converters. Within each converter is an amplifier that has
sufficient gain to set the overall noise temperature of the
receiver. After this first conversion the IF paths are
identical. The 4-40 GHz IF is split at 22 GHz by a diplexer.
The upper half is shifted down to 4-22 GHz with a single block
conversion using high side injection at 44 GHz. Gain is
provided along the way as needed. At this point we have four
4-22 GHz IF paths.)
- All components are on hand and have been
characterized. Noise temperature of 4 and 7 eV for the lower band
of the two converters
- Mounting bracket is finished and RF
converters are now being installed.
- (The
IF module breaks the 4-22 GHz band into 8 bands, each about 2
GHz wide. The pass bands do not overlap and the filter were
chosen to avoid energy in one channel affecting the measure of
an adjacent channel more than the prescribed 0.1%. The square
law detectors that provide a measure of the power in each
channel follow the filters. The detected outputs are connected
to video amps).
- All components are on hand and are being
tested.
- The low loss, high frequency cable, which
interconnects the RF and IF section, is ready for
installation.
- The rack mounted box are being assemble,
one for each IF module.
- Detector/Video Amplifier module - The
following two options are being developed in parallel.
Option
1: UC
Davis is working on providing an
integrated video amp, RF detector, and IF amp module. The first
prototype module should be available in the near
future.
Option 2: We have constructed video
amplifier units (6 prototype) with connectorized RF detectors.
These boards have a gain of 100 and a bandwidth of 1MHz. These
have been tested and are ready for fabrication of the required 32
units. Gary Hallock is also going to use this design for 32
channels of PCI detectors. In addition we are going to construct a
number of board with a slightly different gain/bandwidth (1000/100
kHz) for the DIII-D ECE system additions.
- (This
system is composed of two sets of digitizers, one fast for
fluctuation measurements and another slower set for full shot
profile measurements)
- Slow System - 32 channels of dsp
technology TRAQ modules providing 10 kHz data for the entire CMOD
discharge. These units are now being tested at the
FRC.
- Fast System - 32 channels of LeCroy 6810
units providing up to 1MHz with 128,000 samples per channel. These
units are now also being tested at the FRC.
- CMOD Data
Tree - a prototype has been designed
and is now being installed on CMOD system. All calibration
parameters will be stored in the tree and an IDL program is now
being written to input this parameters with full error
checking.
