use of water calorimetry to discover the critical heat flux for
coolant tube burnout are examples.
5) Development of non-destructive evaluation techniques
for use in the International Thermonuclear Experimental
Reactor (ITER) qualification tests and feedback control
systems. An example of a non-destructive technique is a real-
time, radiation-hardened diagnostic for reliable detection of
intense boiling, such as acoustic emission, which can be used
to detect the onset of critical heat flux limits and provide
active feedback to safety control systems to mitigate tube
burnout. Another example is IR thermography screening
which involves passing a well-defined slug of hot water
through a cold component (a thermal Heaviside function) and
measuring the rate and uniformity of surface temperature
increase. This technique is used to ascertain the integrity and
thermal efficiency of braze joints.
When performing thermal shock experiments on the EBTS,
a water-cooled, computer-controlled, x-y table is used to
process as many as 32 2.5 cm x 2.5 cm x 1.0 cm passively
cooled, v-notched,, shock specimens under one pump down.
During fatigue testing, "A-B" or "A-B-C" cycles are used to
deflect a continuous beam to different areas on the target or to
several different targets with dwell times as short as 100 ms.
This cycle is created by using a wave generator(s) to input a
square wave(s) into the beam raster offset control. This is a
very efficient technique when performing thousands of
fatigue cycles on targets which reach equilibrium very
quickly, In many instances, it permits water calorimetry to be
used for a continual check of absorbed power in an actively
cooled target. The other mode used for fatigue testing is to
perform separate shots by cycling the beam on and off for the
required number of cycles and on/off durations using
computer control. This mode is effective when testing
massive, mechanically attached, passively cooled targets
which require long times to reach steady state temperatures,
particularly on cooldown.
The diagnostics of the facility are designed to gather
comprehensive data from a variety of energy deposition
experiments. A video monitoring system and an infrared
camera and colorizing system are used to observe all tests in
the EBTS. Video recorders are used to document all video
signals that can be analyzed with a frame-by-frame playback
system. A high-speed movie camera with a 10,000 frames/s
maximum speed is also available to record rapid sequences of
events. An array of optical and IR pyrometers is used to
monitor the sample surface temperatures in conjunction with
the IR camera over a range of 20 to 3000 *C. The bulk thermal
response of the sample is measured with a bank of imbedded
thermocouples to record the internal temperature distribution.
Strain gauges are used to measure the mechanical response of
structural members. A residual gas analyzer (RGA) is used to
measure the temporal history and quantities of evolved gas
species.
The post-experiment analysis of high heat flux testing in
the EBTS involves many in-house capabilities. Data analysis
involves the processing of recorded data such as the
extraction of temperature contours using IR camera records or
the comparison of thermocouple records over a series of tests.
Processed data such as temperature profiles, calorimetry data,
mechanical responses, and thermal hydraulic results are
compared with predictions from analytical models. After
samples are removed from the EBTS, they are subjected to
further characterization such as scanning electron microscopy

(SEM), profilometry, surface analysis (EDX, ESCA, AES,
SIMS), and cross sectioning for metallographic studies.
THE EB-1200
The EB-1200 is a dual triode-type, solid cathode,
varioanode electron gun system which can produce 1.2 MW of
electron beam power. The system is designed to study the
thermal response of medium-sized, high heat flux
components under energy depositions of the magnitude and
duration expected in fusion devices. The EB-1200 was built
primarily for HHF testing of actively cooled beryllium clad
divertor and first wall components for the ITER program and
carbon-carbon clad plasma facing components for the
Princeton Tokamak Physics Experiment (TPX). The EB-1200
is comprised of two EH 600 S Von Ardenne electron guns each
equipped with dual focusing and deflection coils. The beams
can be rastered at 10 kHz for high heat flux testing. A
schematic of the EB-1200 system is shown in Figure 2. Table
3 describes the operating parameters for the EB-1200 system.
Targergt
Target         -   -                 Chamber
l m -,
FIGURE 2. EB-1200 SCHEMATIC - TOP VIEW SHOWING
LOCATION OF ELECTRON GUNS.
TABLE 3. EB-1200 OPERATING PARAMETERS

Beam Power
Accelerating Voltage
Beam Current
Angle of Beam Incidence
Cathode Lifetime
Magnetic Lenses
Magnetic Deflection
Max. Angle of Beam
Deflection
Maximum Raster Frequency
Unrastered (pulsed) Spot
Diameter at 600 kW and a
Distance of 1.5 m
Maximum Heat Flux
(unrastered)
Maximum Heated Area
at 1.5 m, 10 kHz
Heat Flux at Maximum Area
Maximum Pressure in
Chamber
Cooling Water Consumption

0 to 1200 kW (cw)
0 to 40 kV
15 amperes each gun
00to900
200 hours
2 coils
2 yokes (orthogonal)
30 at < 200 Hz
70 at 10 kHz
10 kHz
3.5 cm
>1000 MW/m2
37 cm x 37 cm
8.7 MW/m2
S3 Pa
2.2 m3/hr