Transcript LANSCE MPG
LANSCE Master Pattern Generator LANSCE Master Pattern Generator Eric Björklund LANSCE-8 Controls Software (LA-UR-05-2848) LANSCE Master Pattern Generator Features of the LANSCE Timing System • 96 Timing Gates. – Centrally Generated. – Distributed on Coax and Fiber From MPG. • 120 Hz Operation. • Machine cycle is 8.222 milliseconds. – Start of cycle synchronized with AC Line crossing (positive and negative slope). – Timing Gates Clocked by 2.8 Mhz Ring Revolution Frequency. • 1 Second Super-Cycle (120 Cycles). • Versatile (and therefore complex) facility: – 3 flavors of H- beam – 2 flavors of H+ beam – Single Shot & Continuous Mode Capability for Any Beam Flavor. LANSCE Master Pattern Generator Special Requirements (Mostly Age-Related) • Reliability is important. – It can take up to 2 hours to recover from a 1 second loss of RF-gates. • Evenness is also important. – Absolute requirement for some gates: • RF gates • Neutron Choppers – Less of an issue for other gates: • Isotope production • Single-Shot experiments • Irradiation Experiments LANSCE Master Pattern Generator Current Architecture of LANSCE Timing System Timing Gates Timing Distribution Master Timer Timing Gate Generators • Star configuration • 4 redundant gate generator sets in 2 CAMAC crates. • Gate generators are loaded by Master Timer computer, then run independently. • Master Timer computer checks the output of the gate generators and automatically switches to another set when a discrepancy is seen. MUX LANSCE Master Pattern Generator Tools To Generate the Pattern – Delay and Width ; ; Low Frequency RF Gate ; M(LFRF) = 30 D(LFRF) = D(LBEG) - 400 E(LFRF) = D(SREX) ; ; Storage Ring Extraction Window ; M(SREW) = 30 D(SREW) = E(LBEG) - 50 E(SREW) = D(EKLF) ; ; Storage Ring Extraction Gate ; M(SREX) = 30 D(SREX) > D(SREW) + 50 L(SREX) = 10 ; ; LANSCE Chopper Synchronization Gate ; RR(LSYC) = 20 D(LSYC) = D(T0) - 100 E(LSYC) = D(EKLF) + 125 ; ; LANSCE Fast Chopper Synch Gate ; RR(LFCG) = 120 M(LFCG) = 0 D(LFCG) = D(EKLF) L(LFCG) = 25 • • • LANSCE uses a rule-based system to generate the placement of timing gates within a machine cycle. Configuration file contains rules for either automatically setting a gate’s delay and width, or providing limits on acceptable values. A special parser reads the configuration file and generates a subroutine that is compiled and linked into the MPG program. LANSCE Master Pattern Generator Tools To Generate the Pattern – Super-Cycle Layout • • “Mode” rules determine which gates may occur on which machine cycles. Cycles are assigned based on requested rep-rate and mode constraints. – Keep the three H- flavored gates on separate cycles. – Keep the two H+ flavored gates on separate cycles. – Keep the high-power H+ flavored gates and high-power H- flavored gates on separate cycles. • Prioritizes order in which gates are assigned. Mode 0 1 2 3 4 5 6 7 Name ANY 201 PREDECESSOR 805 PREDECESSOR RFAL PREDECESSOR RFAM PREDECESSOR RFAS PREDECESSOR 201 COINCIDENT 805 COINCIDENT Base Gate None 201R 805R RFAL RFAM RFAS 201R 805R Definition May occur on any cycle May only occur on cycles preceding 201R gates May only occur on cycles preceding 805R gates May only occur on cycles preceding RFAL gates May only occur on cycles preceding RFAM gates May only occur on cycles preceding RFAS gates May only occur on cycles with 201R gates May only occur on cycles with 805R gates LANSCE Master Pattern Generator Tools To Generate the Pattern – Super-Cycle Layout • Theoretical Framework Developed for Evenly Distributing Gates Across the Super-Cycle. – – – – Completely even distribution for unconstrained gates with rep-rates that evenly divide 120. O(n) time. Most even distribution possible for unconstrained gates with rep-rates that do not evenly divide 120. O(n) time. Most even distribution possible for constrained gates whose “ideal” patterns map into the available cycles. O(n2) time. whose Good heuristics for constrained gates “ideal” patterns do not map into the available cycles. O(n) – O(n5) time. 2 2 n / 2 n1 jm Ugliness j i n j1 i 0 n LANSCE Master Pattern Generator Tools To View The Generated Pattern Time Plot • “Micro” view of a single “generic” cycle. • Shows gate relationships within the machine cycle. LANSCE Master Pattern Generator Tools To View The Generated Pattern Rep-Rate Plot • “Macro” view of the Super-Cycle. • Shows which gates are assigned to which cycles.