Upgrading the Fermilab Linac local control system Page: 3 of 3
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system for making settings.
The modulator provides a 180 KV, 141 ampere, 128 |is
pulse to the klystron. It appears to a Linac control station as,
simply, a self-regulating, self-protecting high-voltage power
supply. The control station generates a 16-bit voltage setting for
the modulator system. Several analog and digital readbacks are
provided. The local intelligence for the modulator is responsible
1. IS Hz closed-loop control in the modulator;
2.15 Hz readout of local analog and digital information;
3. transient recording of pertinent waveforms within the
4. fast closed-loop/feed-forward control to insure that the
proper level of voltage regulation (0.1%) is obtained.
One VME crate per modulator, two per control station, are nec-
essary for noise suppression. The transient waveforms are sorted
according to the condition of the modulator—most are recorded
as “good" waveforms, but the real purpose of this capability is to
access the waveforms generated during a failure of the modulator.
These waveforms can be accessed in the VME memory of the
modulator crate over the VI. Although the amount of data stored
for these transient waveforms is large (several MBytes), it is
thought that the frequency they are viewed will be small.
The low-level RF hardware runs in the VXIbus environment.
This system is responsible for providing an RF signal of the cor-
rect phase and amplitude to the 300-watt klystron-driver ampli-
. fier so that beam is properly accelerated through the cavity. The
local VXI microprocessor will generate and adaptively change
that waveform according to phase and amplitude information ob-
tained from recent beam pulses: “adaptive feed-forward.” Two
klystrons will be fed from a single VXI crate containing two low-
level RF hardware modules. As discussed above, readings and
settings to this system from the master control station will be
done through VME/VXI memory over a VI.
The beam diagnostics  provide several analog signals
which are read through a sample-and-hold/RM. Since the aper-
ture of the new linac is significantly smaller than the old linac (3
cm vs 4 cm), we are going to implement a local application (see
below) to actively keep the beam in the center of the beam pipe.
It is likely that a local application will also be needed to assist
with the measurements for the “At” experiment ,
The interface to the klystron interlocks/safety system is
through several (twenty) bits in a RM at each RF station. A
computer-reset and a computer-ready bit are provided. (Natu-
rally, the primary safety aspects of the accelerator are contained
in the hardware. The computer controls system is not part of the
safety system.) The water system interface is through a RM.
Also present at each control station is a color computer
console. This console uses the Macintosh Dei computer with an
Apple TokenTalk Nubus card. The applications presently avail-
able are a color parameter page, a parameter plotting package and
a VME memory-dump page. These programs are quite mature
and reflect the standard Macintosh “look-and-feel.” Additionally,
we have a token ring driver to the LabView package.
Several aspects of the local controls software need to be
mentioned explicitly. The software is being developed to have
each local station respond directly to data requests generated
from the consoles in the Main Control Room, thus eliminating the
need for a protocol-translating front-end computer. These con-
soles communicate via the Accelerator Controls Network (AC-
NET) protocol which die other accelerator controls subsystems at
Fermilab use. Each Linac control station is to recognize two sorts
of network message protocols, the original (“classic”) protocol,
used in communication between control stations, and the ACNET
A critical part of the control station software is supporting
multiple, simultaneous, local control procedures. Each local sta-
tion now has the ability to run many “Local Applications,” or
LAs. The LAs being implemented now include:
1. 201-MHz system recovery, e.g., from a modulator
2. DTL quad reset;
3. 805-MHz system water temperature stabilization (note:
there will be four cavity water systems and a klystron water sys-
tem for each RF system: that’s ten water loops per control
4. beam steering;
5.805-MHz tum-on and turn-off;
6. low-energy emittance scan.
The software for die smart rack monitor is not settled yet.
The MC68332 is based on the MC68020, so most, but not all, of
the instructions of die ’020 are in the '332. The hope is that we
can implement simple but extensible software on die '332 which
allows, initially, the SRM to behave like a dumb RM. Then, fea-
tures could be added to support SRM local applications.
The control system for the Fermilab linac has been,
redesigned. The old linac control system is to be replaced in the
summer of 1991 by one similar to that required to operate the 805
MHz/400 MeV linac. The old D/A and A/D hardware is retained
on the old RF systems. The control system for the new linac re-
quires some new techniques, in particular, interfacing with
several smart subsystems. The two types of local control are de-
signed to work together to control the whole new linac in a
coherent, integrated and efficient fashion
 R. Goodwin and M. Shea. “The Distributed Control System for the
Fermilab 200 MeV Linac,” Proceedings of the 1981 Linac Confer-
ence, pp 277-280.
 R. Noble, “The Fermilab Linac Upgrade," this conference, talk
 R. Goodwin, el al.. “Initial Operation and Current Status of the Fer-
milab DZero VMEB US-Based Hardware Control and Monitoring
System,” proceedings of the 1989 International Conference on Ac-
celerator and Large Experimental Physics Control Systems, Van-
couver, BC, Canada.
 M. Shea, “Smart Rack Monitor,” internal note, available from the
 The modulator, low-level RF and safety systems are in the design
phase. The best reference so far on these systems is found in the
design report for the 400 MeV Fermilab Linac.
 “Diagnostics for the 400 MeV Fermilab Linac,” Elliott S. McCrary,
Glenn Lee and Robert Webber, tins conference, talk number TU4-1
 T. Owens and E. McCrary, “The Delta-t procedure at Fermilab,” at
this conference, paper TH4-51.
 This product is available from National Instruments in Austin, TX.
Additionally, a Unix interface to the token ring VME data hat been
written and a parameter page, plot package and a token ring driver
to the Data Views package, available from VI Corporation in Am-
herst, MA, have been written. The Unix software is somewhat mote
capable, but a lot less mature than the Macintosh software.
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McCrory, E.S.; Goodwin, R.W. & Shea, M.F. Upgrading the Fermilab Linac local control system, article, February 1, 1991; Batavia, Illinois. (digital.library.unt.edu/ark:/67531/metadc1100591/m1/3/: accessed November 12, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.